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 Title
 On Elliptic Fibrations and FTheory Compactifications of String Vacua.
 Creator

Fullwood, James, Aluﬃ, Paolo, Reina, Laura, Van Hoeij, Mark, Aldrovandi, Ettore, Hironaka, Eriko, Department of Mathematics, Florida State University
 Abstract/Description

We investigate some algebrogeometric aspects of several families of elliptic fibrations relevant for Ftheory model building along with some physical applications. In particular, we compute topological invariants of elliptic fibrations via `SethiVafaWitten formulas', which relate the given invariant of the total space of the fibration to invariants of the base. We find that these invariants can often be computed in a baseindependent manner, and moreover, can be computed for all possible...
Show moreWe investigate some algebrogeometric aspects of several families of elliptic fibrations relevant for Ftheory model building along with some physical applications. In particular, we compute topological invariants of elliptic fibrations via `SethiVafaWitten formulas', which relate the given invariant of the total space of the fibration to invariants of the base. We find that these invariants can often be computed in a baseindependent manner, and moreover, can be computed for all possible dimensions of a base at once. As such, we construct generating series $f(t)$ corresponding to each invariant such that the coefficient of $t^k$ encodes the invariant of the elliptic fibration over a base of dimension $k$, solely in terms of invariants of the base. From the Ftheory perspective, we highlight aspects of elliptic fibrations other than Weierstrass models, and construct a new orientifold limit of Ftheory associated with $D_5$ fibrations, i.e., elliptic fibrations whose elliptic fiber is realized via a complete intersection of two quadrics in $\mathbb{P}^3$. We verify tadpole relations as predicted by the (conjectural) equivalence between Ftheory and typeIIB, as well as `universal tadpole relations', which are mathematical generalizations of the tadpole relations predicted by the physics of Ftheory. We also simplify formulas for invariants of CalabiYau fourfolds, and suggest that all Hodge numbers of CalabiYau fourfolds depend linearly on $c_1(B)^3$, where $B$ is the base of the fibration.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd4848
 Format
 Thesis
 Title
 Quantum Phase Transitions and Enhancement of Superconductivity by a Parallel Magnetic Field in Two Dimensional Superconductors.
 Creator

Gardner, H. Jeffrey, Xiong, Peng, Larbalestier, David, Schlottmann, Pedro, Chiorescu, Irinel, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

This dissertation describes several studies of superconducting phenomena in two dimensions. We have investigated the superconductorinsulator quantum phase transitions (SITs) tuned by several parameters, namely disorder (d), magnetic field (B), and magnetic impurities (MI). The films have been examined through electrical transport measurements and tunneling spectroscopy. Our experiments are carried out in a unique experimental setup which has allowed us to study these three SITs in situ on...
Show moreThis dissertation describes several studies of superconducting phenomena in two dimensions. We have investigated the superconductorinsulator quantum phase transitions (SITs) tuned by several parameters, namely disorder (d), magnetic field (B), and magnetic impurities (MI). The films have been examined through electrical transport measurements and tunneling spectroscopy. Our experiments are carried out in a unique experimental setup which has allowed us to study these three SITs in situ on the same sample. There are two major theoretical frameworks to describe the superconductorinsulator transitions. One theory calls for a transition from a superconductor to a fermionic insulator. The other points to an bosonic insulator with localized Cooper pairs and itinerant vortices. Our experimental capabilities let us make direct comparisons of the SITs and comment on the nature of transition. We consider the MItuned SIT a canonical example of an SIT in the fermionic framework. The resistive transitions in the superconducting state are sharp, the phase boundary is well defined, and the insulating state shows weakly insulating behavior. The Btuned SIT is representative of a bosonic SIT. In this case, the resistive transitions broaden as magnetic field strength is increased and there is no distinct boundary between the superconducting and insulating phases. Transport reveals a likely activated behavior just on the insulating side of the transition indicative of localized superconductivity. At higher magnetic fields, the temperature dependence weakens, possibly to logarithmic, signaling a break up of Cooper pairs into single electrons. Direct evidence of localized Cooper pairs comes via tunneling spectroscopy measurements on dtuned granular films where full, bulk superconducting energy gaps are measured in the global insulating state. We have performed transport and tunneling spectroscopy measurements of the dtuned SIT on amorphous Pb films. The transport behavior is qualitatively similar to what we observed for the MItuned SIT. We will also show that our observations of the Btuned SIT on amorphous Pb films are analogous to the dtuned SIT on granular films. One goal of our studies was to use tunneling spectroscopy to probe the nature of the insulating states of the dtuned and MItuned SITs. We were only able to complete preliminary measurements on the dtuned transition, however they are consistent with previous experiments in which increasing disorder leads to a decrease of TC and a concomitant suppression of the normal state density of state (DOS). Our inhouse designed and fabricated sample rotation system affords us the opportunity to study the same sample in both perpendicular and parallel magnetic field orientations in situ without breaking vacuum. This capability led us to the observation of parallel magnetic field enhanced superconductivity in amorphous Pb films and the 2D electron gas at the heteroepitaxial interface of the band insulators LaAlO3 and SrTiO3. We found that the mean field TC of the aPb films can be enhanced by as much as 13% above the zerofield value. A qualitatively similar fieldenhancement effect has been observed in the LaAlO3/SrTiO3 interfacial superconductor. Moreover, our experiments show the fieldenhancement is strongly dependent on the film thickness and magnetic impurity concentration. Clearly, the Bardeen Cooper Schrieffer (BCS) and GinzburgLandau (GL) theories of superconductivity do not contain the physics which would account for fieldenhanced superconductivity. Presently, we do not have a complete theoretical understanding of the enhancement effect. However, our experimental results have placed significant constraints on any viable theoretical model. In this dissertation, several theoretical explanations of parallel fieldenhanced superconductivity are discussed and compared with our observations.
Show less  Date Issued
 2011
 Identifier
 FSU_migr_etd4855
 Format
 Thesis
 Title
 Chern Classes of Sheaves of Logarithmic Vector Fields for Free Divisors.
 Creator

Liao, Xia, Aluﬃ, Paolo, Reina, Laura, Klassen, Eric P., Aldrovandi, Ettore, Petersen, Kathleen, Department of Mathematics, Florida State University
 Abstract/Description

The thesis work we present here focuses on solving a conjecture raised by Aluffi about ChernSchwartzMacPherson classes. Let $X$ be a nonsingular variety defined over an algebraically closed field $k$ of characteristic $0$, $D$ a reduced effective divisor on $X$, and $U = X smallsetminus D$ the open complement of $D$ in $X$. The conjecture states that $c_{textup{SM}}(1_U) = c(textup{Der}_X(log D)) cap [X]$ in $A_{*}(X)$ for any locally quasihomogeneous free divisor $D$. We prove a stronger...
Show moreThe thesis work we present here focuses on solving a conjecture raised by Aluffi about ChernSchwartzMacPherson classes. Let $X$ be a nonsingular variety defined over an algebraically closed field $k$ of characteristic $0$, $D$ a reduced effective divisor on $X$, and $U = X smallsetminus D$ the open complement of $D$ in $X$. The conjecture states that $c_{textup{SM}}(1_U) = c(textup{Der}_X(log D)) cap [X]$ in $A_{*}(X)$ for any locally quasihomogeneous free divisor $D$. We prove a stronger version of this conjecture. We also report on work aimed at studying the Grothedieck class of hypersurfaces of low degree. In this work, we verified the Geometric ChevalleyWarning conjecture in several low dimensional cases.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd7467
 Format
 Thesis
 Title
 Topics in Physics Beyond the Standard Model.
 Creator

OPP, Karoline K., Okui, Takemichi, Aldrovandi, Ettore, Reina, Laura, Adams, Todd, Gerardy, Christopher, Department of Physics, Florida State University
 Abstract/Description

In this work, topics in physics beyond the standard model of high energy phyics relevant to the experimental studies at the Large Hadron Collider (LHC) at CERN are discussed. We introduce an effective theory to describe the dynamics of heavy Majorana particles, whose existence is predicted in many extensions of the standard model. Further, it is demonstrated how by combining the two independent concepts of a weakly interacting massive particle accounting for the dark matter observed in our...
Show moreIn this work, topics in physics beyond the standard model of high energy phyics relevant to the experimental studies at the Large Hadron Collider (LHC) at CERN are discussed. We introduce an effective theory to describe the dynamics of heavy Majorana particles, whose existence is predicted in many extensions of the standard model. Further, it is demonstrated how by combining the two independent concepts of a weakly interacting massive particle accounting for the dark matter observed in our universe and gauge coupling unification, strong phenomenological trends can be inferred. The scenario we present predicts new colored states within LHC reach that can be either collider stable or decay promptly to final states including a Higgs particle. In both cases, interesting LHC signatures are expected. The LHC discovery of the long predicted Higgs boson as well as new lower bounds on supersymmetric particle masses provide motivation to reevaluate the issue of finetuning in supersymmetric theories. We provide an overview of the current state of this ongoing discussion. In the last part of this work we introduce an alternative approach termed stable nearcriticality, in which the standard limits on superparticle masses stemming from finetuning considerations are relaxed. This approach requires specific and robust correlations among soft mass terms. We discuss how reduced finetuning can be achieved even if the gauge and Yukawa couplings are considered variable parameters. Finally, we illustrate our findings with a possible model implementation and demonstrate the validity of our approach by analysing a representative benchmark point.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd7451
 Format
 Thesis
 Title
 HeavyQuark Associated Production with One Hard Photon at Hadron Colliders.
 Creator

Hartanto, Heribertus Bayu, Reina, Laura, Aluﬃ, Paolo, Owens, Joseph F., Askew, Andrew, Capstick, Simon, Department of Physics, Florida State University
 Abstract/Description

We present the calculation of heavyquark associated production with a hard photon at hadron colliders, namely pp(p pbar) > Q Qbar gamma +X (for Q = t, b), at NexttoLeading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For t tbar gamma production we observe a sizeable reduction of the renormalization and factorization scale...
Show moreWe present the calculation of heavyquark associated production with a hard photon at hadron colliders, namely pp(p pbar) > Q Qbar gamma +X (for Q = t, b), at NexttoLeading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For t tbar gamma production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for b bbar gamma production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving b quarks and vector bosons and we explain its origin in detail. For b bbar gamma production we study both the case in which at least one b jet and the case in which at least two b jets are observed. We perform the b bbar gamma calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one b jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for p pbar > gamma + b + X with Tevatron data.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd7411
 Format
 Thesis
 Title
 OnShell Methods Applied to Exotic Higgs Production at Hadronic Colliders.
 Creator

Thayer, Benjamin J. (Benjamin Joseph), Reina, Laura, Aluﬃ, Paolo, Prosper, Harrison B., Okui, Takemichi, Capstick, Simon, Department of Physics, Florida State University
 Abstract/Description

ABSTRACT We calculate the associated production of a pseudoscalar (A) with a pair of heavy quarks at hadonic colliders, namely p pbar, pp →QQA + X for Q = b, t and X the remaining partonic interactions, including oneloop QCD corrections, i.e. at Nexttoleading Order (NLO) in QCD. The oneloop amplitude for the parton level processes q qbar, gg → Q Qbar A is calculated both with a traditional Feynmandiagram approach and with more recently proposed onshell methods and unitarity based...
Show moreABSTRACT We calculate the associated production of a pseudoscalar (A) with a pair of heavy quarks at hadonic colliders, namely p pbar, pp →QQA + X for Q = b, t and X the remaining partonic interactions, including oneloop QCD corrections, i.e. at Nexttoleading Order (NLO) in QCD. The oneloop amplitude for the parton level processes q qbar, gg → Q Qbar A is calculated both with a traditional Feynmandiagram approach and with more recently proposed onshell methods and unitarity based techniques. We use this process as a testing ground to learn and compare the new onshell methods to more traditional techniques in a case where several massive particles are involved. We present results for the full NLO hadronic cross section, at both the Tevatron (p pbar) and the Large Hadron Collider (pp) with the aim to further aid and constrain the parameter space of models with pseudoscalar production at particle colliders.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd5228
 Format
 Thesis
 Title
 Sequences of PseudoAnosov Mapping Classes with Asymptotically Small Dilatation.
 Creator

Valdivia, Aaron David, Hironaka, Eriko, Reina, Laura, Heil, Wolfgang, Klassen, Eric, Department of Mathematics, Florida State University
 Abstract/Description

We construct sequences of pseudoAnosov examples which we use to bound the minimal dilatation on arbitrary surfaces. We show that these bounds give the asymptotic behavior of the minimal dilatations for certain sequences. Further we show that the mapping classes for a given sequence from our construction can be realized as fibrations of a single 3manifold.
 Date Issued
 2011
 Identifier
 FSU_migr_etd5242
 Format
 Thesis
 Title
 Search for Contact Interactions Using the Inclusive Jet √ pT Spectrum in PP Collisions at S = 7 TeV.
 Creator

Haas, Jeffrey David, Prosper, Harrison B., Aldrovandi, Ettore, Reina, Laura, Adams, Todd, Eugenio, Paul, Department of Physics, Florida State University
 Abstract/Description

Results are reported of a search for a deviation in the jet production cross section from the prediction of perturbative quantum chromodynamics at nexttoleading order. The search is conducted using a 7 TeV protonproton data sample corresponding to an integrated luminosity of 5.0 fb1 , collected with the Compact Muon Solenoid detector at the Large Hadron Collider. A deviation could arise from interactions characterized by a mass scale &Lambda too high to be probed directly at the LHC. Such...
Show moreResults are reported of a search for a deviation in the jet production cross section from the prediction of perturbative quantum chromodynamics at nexttoleading order. The search is conducted using a 7 TeV protonproton data sample corresponding to an integrated luminosity of 5.0 fb1 , collected with the Compact Muon Solenoid detector at the Large Hadron Collider. A deviation could arise from interactions characterized by a mass scale &Lambda too high to be probed directly at the LHC. Such phenomena can be modeled as contact interactions. No evidence of a deviation is found. Using the CLs criterion, lower limits are set on &Lambda of 9.9 TeV and 14.3 TeV at 95% confidence level for models with destructive and constructive interference, respectively. Limits obtained with a Bayesian method are also reported.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd7405
 Format
 Thesis
 Title
 Search for Multiply Charged Heavy Stable Charged Particles in Data Collected with the CMS Detector.
 Creator

Veeraraghavan, Venkatesh, Adams, Todd, Steinbock, Oliver, Prosper, Harrison, Reina, Laura, Capstick, Simon, Department of Physics, Florida State University
 Abstract/Description

Several models of new physics yield particles that are massive, longlived, and have an electric charge, Q, greater than that of the electron, e. A search for evidence of such particles was performed using 5.0 fb1 and 18.8 fb1 of protonproton collision data collected at √s=7 TeV and √s=8 TeV, respectively, with the Compact Muon Solenoid detector at the Large Hadron Collider. The distinctive detector signatures of these particles are that they are slowmoving and highly ionizing. Ionization...
Show moreSeveral models of new physics yield particles that are massive, longlived, and have an electric charge, Q, greater than that of the electron, e. A search for evidence of such particles was performed using 5.0 fb1 and 18.8 fb1 of protonproton collision data collected at √s=7 TeV and √s=8 TeV, respectively, with the Compact Muon Solenoid detector at the Large Hadron Collider. The distinctive detector signatures of these particles are that they are slowmoving and highly ionizing. Ionization energy loss and timeofflight measurements were made using the inner tracker and the muon system, respectively. The search is sensitive to 1e ≤ Q ≤ 8e. Data were found to be consistent with standard model expectations and upper limits on the production cross section of these particles were computed using a DrellYanlike production model. Masses below 517, 687, 752, 791, 798, 778, 753, and 724 GeV are excluded for Q=1e, 2e, 3e, 4e, 5e, 6e, 7e, and 8e, respectively.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd8651
 Format
 Thesis
 Title
 Nuclear Magnetic Resonance in OptimallyDoped YBCO and the Electronic Phases of Bilayer Graphene.
 Creator

Throckmorton, Robert E. (Robert Emil), Vafek, Oskar, Cross, Timothy, Bonesteel, Nicholas, Boebinger, Gregory, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

We treat two different problems in condensed matter physics. The rst concerns nuclear magnetic resonance (NMR) in optimallydoped YBCO in the mixed state. We show that the line shape is broadened due to the fact that the Knight shift becomes positiondependent in the mixed state. We also identify a second mechanism, in which a pair of spin up quasiparticles is emitted or absorbed, by which the nuclear spins can relax in the presence of a magnetic field, and show that this second mechanism...
Show moreWe treat two different problems in condensed matter physics. The rst concerns nuclear magnetic resonance (NMR) in optimallydoped YBCO in the mixed state. We show that the line shape is broadened due to the fact that the Knight shift becomes positiondependent in the mixed state. We also identify a second mechanism, in which a pair of spin up quasiparticles is emitted or absorbed, by which the nuclear spins can relax in the presence of a magnetic field, and show that this second mechanism dominates at low temperatures. We then compare our results to experimental data on O17 NMR and show that it is possible to explain the data without invoking the presence of antiferromagnetic correlations in the vortex cores. In fact, we show that the effects of such correlations on the O17 relaxation rates are suppressed in the mixed state, as they are in the normal state. The second problem concerns the electronic phases of bilayer graphene at half filling. Using finitetemperature weakcoupling RG methods, we are able to analytically determine all possible outcomes of the RG ow equations for the nine coupling constants. From this, we are able to determine all of the possible leading instabilities that the system may exhibit as its temperature is lowered. We find that the full phase diagram exhibits a very rich structure, with many different possible instabilities. We then specialize to the case of finite range densitydensity interactions. We introduce such an interaction into the microscopic tightbinding model and show how it can be related to the coupling constants in the lowenergy effective theory, and apply these results to determine the leading instabilities of the system as a function of the range of the interaction. We consider two forms of the interaction, both motivated by experimental setups, namely a potential like that produced by an electron in the presence of an infinite conducting plate, and like that produced by an electron situated exactly halfway between two infinite conducting plates. We nd that the system is unstable to an antiferromagnetic phase for shortranged interactions and towards a nematic phase, which breaks the rotational symmetry of the lattice, in agreement with previous work. While the antiferromagnetic phase is gapped, the nematic phase is gapless. Motivated by the fact that we find an instability towards an antiferromagnetic phase for shortranged interactions and by experimental data that suggests the presence of a gap, we then turn our attention to an investigation of the antiferromagnetic phase in the presence of an applied magnetic field. This is done within the framework of variational mean field theory. We find that, at low fields, the antiferromagnetic order parameter (B) ô (0) B2. At higher elds, for which !c is larger than about 2&Delta(0), we find that &Delta(B) = &omega_c=[ln(&omega_c/&Delta(0)) + C], where C = 0.67 and omega_c = eB=m^* c is the cyclotron frequency. We also determine the energy gap for creating electronhole excitations in the system, and, at high elds, we nd it to be a!c + 2(B), where a is a nonuniversal, interactiondependent, constant.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd5448
 Format
 Thesis
 Title
 Periods and Motives: Applications in Mathematical Physics.
 Creator

Li, Dan, Marcolli, Matilde, Reina, Laura, Aluﬃ, Paolo, Agashe, Amod, Aldrovandi, Ettore, Department of Mathematics, Florida State University
 Abstract/Description

The study of periods arose in number theory and algebraic geometry, periods are interesting transcendental numbers like multiple zeta values, on the other hand periods are integrals of algebraic differential forms over domains described by algebraic relations. Viewed as abstract periods, we also consider their relations with motives. In this work, we consider two problems in mathematical physics as applications of the ideas and tools from periods and motives. We first consider the algebro...
Show moreThe study of periods arose in number theory and algebraic geometry, periods are interesting transcendental numbers like multiple zeta values, on the other hand periods are integrals of algebraic differential forms over domains described by algebraic relations. Viewed as abstract periods, we also consider their relations with motives. In this work, we consider two problems in mathematical physics as applications of the ideas and tools from periods and motives. We first consider the algebrogeometric approach to the spectral theory of Harper operators in solid state physics. When the parameters are irrational, the compactification of its Bloch variety is an indprovariety, which is a Cantorlike geometric space and it is compatible with the picture of Hofstadter butterfly. On each approximating component the density of states of the electronic model can be expressed in terms of period integrals over Fermi curves, which can be explicitly computed as elliptic integrals or periods of elliptic curves. The above density of states satisfies a PicardFuchs equation, whose solutions are generally given by hypergeometric functions. We use the idea of mirror maps as in mirror symmetry of elliptic curves to derive a qexpansion for the energy level based on the PicardFuchs equation. In addition, formal spectral functions such as the partition function are derived as new period integrals. Secondly, we consider generalized Feynman diagram evaluations of an effective noncommutative field theory of the PonzanoRegge model coupled with matter in loop quantum gravity. We present a parametric representation in a linear kapproximation of the effective field theory derived from a kdeformation of the PonzanoRegge model and define a generalized Kirchhoff polynomial with kcorrection terms. Setting k equal to 1, we verify that the number of points of the corresponding hypersurface of the tetrahedron over finite fields does not fit polynomials with integer coefficients by computer calculations. We then conclude that the hypersurface of the tetrahedron is not polynomially countable, which possibly implies that the hypersurface of the tetrahedron as a motive is not mixed Tate.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd5390
 Format
 Thesis
 Title
 Deconfinement Transition in Equilibrium Lattice Gauge Theory with Realistic Boundary Conditions.
 Creator

Wu, Hao, Berg, Bernd A., Brüschweiler, Rafael, Adams, Todd, Piekarewicz, Jorge, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

Heavyion collision experiments carried out at the Brookhaven National Laboratory, or BNL, and at the European Organization for Nuclear Research, or CERN, provide evidence that matter can be driven from a confined, lowtemperature phase into a deconfined high temperature phase of liberated quarks and gluons. Understanding of the deconfinement transition can bring our knowledge of stronglyinteracting matter to a deeper level. Ab initio equilibrium studies of the thermodynamic equation of...
Show moreHeavyion collision experiments carried out at the Brookhaven National Laboratory, or BNL, and at the European Organization for Nuclear Research, or CERN, provide evidence that matter can be driven from a confined, lowtemperature phase into a deconfined high temperature phase of liberated quarks and gluons. Understanding of the deconfinement transition can bring our knowledge of stronglyinteracting matter to a deeper level. Ab initio equilibrium studies of the thermodynamic equation of state in the deconfined phase are possible in the framework of lattice gauge theory. It is often desired in such studies to approach the infinite volume thermodynamic limit. To accomplish it quickly, most studies have implemented lattices with periodic boundary conditions. However, the physical volumes created at the Brookhaven National Laboratory are small and exploratory work for pure SU(3) lattice gauge theory suggests that boundary effects cannot be neglected. In this work we study the SU(3) deconfined equilibrium phase in small volumes with inside and outside temperatures in the SU(3) scaling region, using a lattice geometry of the doublelayered torus. Our results show substantial finite size effects on the deconfining transition temperature under realistic boundary conditions.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd5461
 Format
 Thesis
 Title
 Functional Data Analysis and Partial Shape Matching in the Square Root Velocity Framework.
 Creator

Robinson, Daniel T., Klassen, Eric, Reina, Laura, Bellenot, Steven, Mio, Washington, Srivastava, Anuj, Department of Mathematics, Florida State University
 Abstract/Description

We investigate two problems in elastic curve shape analysis, working within the context of the square root velocity (SRV) framework. The first of these is to develop specialized algorithms for the analysis of onedimensional curves, which are just realvalued functions. In this particularly simple case, the elastic matching problem can be stated as a finite combinatorial problem in which the optimal solution can be found exactly. We also develop a method for groupwise alignment, and use it to...
Show moreWe investigate two problems in elastic curve shape analysis, working within the context of the square root velocity (SRV) framework. The first of these is to develop specialized algorithms for the analysis of onedimensional curves, which are just realvalued functions. In this particularly simple case, the elastic matching problem can be stated as a finite combinatorial problem in which the optimal solution can be found exactly. We also develop a method for groupwise alignment, and use it to compute Karcher means of collections of functions. Second, we consider the problem of finding optimal partial matches between curves in Euclidean space within the SRV framework, and present algorithms and heuristics to solve this problem. Finally, we give a brief overview of libsrvf, an opensource software library providing implementations of the algorithms developed in the course of this work.
Show less  Date Issued
 2012
 Identifier
 FSU_migr_etd5424
 Format
 Thesis
 Title
 First Measurement of Top Quark Pair Production CrossSection in Muon Plus Hadronic Tau Final States.
 Creator

Sumowidagdo, Suharyo, Adams, Todd, Aldrovandi, Ettore, Wahl, Horst, Reina, Laura, Capstick, Simon, Department of Physics, Florida State University
 Abstract/Description

This dissertation presents the first measurement of top quark pair production crosssection in events containing a muon and a tau lepton. The measurement was done with 1 fb−1 of data collected during April 2002 through February 2006 using the DØ detector at the Tevatron protonantiproton collider, located at Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois. Events containing one isolated muon, one tau which decays hadronically, missing transverse energy, and two or more...
Show moreThis dissertation presents the first measurement of top quark pair production crosssection in events containing a muon and a tau lepton. The measurement was done with 1 fb−1 of data collected during April 2002 through February 2006 using the DØ detector at the Tevatron protonantiproton collider, located at Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois. Events containing one isolated muon, one tau which decays hadronically, missing transverse energy, and two or more jets (at least one of which must be tagged as a heavy flavor jet) were selected.Twentynine candidate events were observed with an expected background of 9.16 events. The top quark pair production crosssection is measured to beσ (t¯t) = 8.0+2.8 −2.4 (stat)+1.8−1.7 (syst) ± 0.5 (lumi) pb.Assuming a top quark pair production crosssection of 6.77 pb for Monte Carlo signal top events without a real tau, the measured σ × BR isσ (t¯t) × BR(t¯t μ +τ + 2ν + 2b) = 0.18+0.13−0.11 (stat)+0.09−0.09 (syst) ± 0.01 (lumi) pb.
Show less  Date Issued
 2008
 Identifier
 FSU_migr_etd0407
 Format
 Thesis
 Title
 SO(10) Supersymmetric Grand Unified Theories: from Cosmology to Colliders.
 Creator

Summy, Heaya Ann, Baer, Howard, Sussman, Mark, Reina, Laura, Wahl, Horst, Manousakis, Efstratios, Department of Physics, Florida State University
 Abstract/Description

Simple SUSY GUT models based on the gauge group SO(10) require tbt Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places a severe constraint on the expected spectrum of superpartners, with scalar masses ~ 10 TeV while gaugino masses are quite light. For Yukawaunified models with μ > 0, the spectrum is characterized by three mass scales: i). first and second generation scalars in the multiTeV range, ii). third generation...
Show moreSimple SUSY GUT models based on the gauge group SO(10) require tbt Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places a severe constraint on the expected spectrum of superpartners, with scalar masses ~ 10 TeV while gaugino masses are quite light. For Yukawaunified models with μ > 0, the spectrum is characterized by three mass scales: i). first and second generation scalars in the multiTeV range, ii). third generation scalars, μ and mA in the fewTeV range and iii). gluinos in the ~ 350−500 GeV range with chargino masses around 100−160 GeV. In such a scenario, gluino pair production should occur at large rates at the CERN LHC, followed by gluino threebody decays into neutralinos or charginos. Discovery of Yukawaunified SUSY at the LHC should hence be possible with only 1 fb−1 of integrated luminosity, by tagging multijet events with 2–3 isolated leptons, without relying on missing ET . A characteristic dilepton mass edge should easily be apparent above Standard Model background. Combining dileptons with bjets, along with the gluino pair production cross section information, should allow for gluino and neutralino mass reconstruction. A secondary corroborative signal should be visible at higher integrated luminosity in the X1±1X20 → 3l channel, and should exhibit the same dilepton mass edge as in the gluino cascade decay signal. A problem generic to all supergravity models comes from overproduction of gravitinos in the early universe: if gravitinos are unstable, then their late decays may destroy the predictions of Big Bang nucleosynthesis. We also present a Yukawaunified SO(10) SUSY GUT scenario which avoids the gravitino problem, gives rise to the correct matterantimatter asymmetry via nonthermal leptogenesis, and is consistent with the WMAPmeasured abundance of cold dark matter due to the presence of an axino LSP. To maintain a consistent cosmology for Yukawaunified SUSY models, we require a reheat temperature TR ~ 106−107 GeV, an axino mass around 0.1−10 MeV, and a PecceiQuinn breaking scale fa ~ 1012 GeV.
Show less  Date Issued
 2008
 Identifier
 FSU_migr_etd0405
 Format
 Thesis
 Title
 Structural Behavior of 157,158,159Dy in the I=30−50L Spin Regime and the HighSpin Domain of 158Er Up to and Above Band Termination.
 Creator

Pipidis, Paschalis Akis, Riley, Mark A., Aldrovandi, Ettore, Piekarewicz, Jorge, Reina, Laura, Eugenio, Paul M., Department of Physics, Florida State University
 Abstract/Description

The question of how do the properties of nuclei evolve with increasing excitation energy and angular momentum is one of the current frontiers in nuclear physics. State of the art $gamma$ray detector systems have been used to investigate this question, in a series of rareearth nuclei with mass extit{A}$sim$158. Significant extensions to the highspin excitation spectrum of the $N$=91, 92, 93 isotopes $^{157,158,159}$Dy have been achieved using the highefficiency $gamma$ray spectrometers...
Show moreThe question of how do the properties of nuclei evolve with increasing excitation energy and angular momentum is one of the current frontiers in nuclear physics. State of the art $gamma$ray detector systems have been used to investigate this question, in a series of rareearth nuclei with mass extit{A}$sim$158. Significant extensions to the highspin excitation spectrum of the $N$=91, 92, 93 isotopes $^{157,158,159}$Dy have been achieved using the highefficiency $gamma$ray spectrometers EUROBALL and GAMMASPHERE. These nuclei were populated via weak 3$n$ or $alpha xn$ exit channels in fusion evaporation reactions. In $^{157}$Dy, the yrast band has been extended to extit{I}$^pi$=$frac{101}{2}^{+}$ (tentatively to $frac{105}{2}^{+}$) with four sideband structures (two of which are new) observed in the 35$$50 $hbar$ spin range. In $^{158}$Dy, three bands have been extended to 42$^{+}$ (44$^{+}$), 40$^{}$, and 41$^{}$ (43$^{}$), while in $^{159}$Dy the yrast band is observed to $frac{81}{2}^{+}$ ($frac{85}{2}^{+}$). A total of 84 (99) new transitions, including 2 new bands, were added to the level schemes of $^{157,158,159}$Dy. The highspin behavior and band crossing systematics of the Dy isotopes and of the neighboring $N$=91, 92, and 93 isotones are discussed in terms of rotational alignments and shape transitions. Cranked NilssonStrutinsky calculations without pairing have been performed for detailed comparisons with the very highspin states observed in $^{157}$Dy. Results on $^{157,158,159}$Dy have been published in extit{Phys. Rev. C.} Moreover, the angularmomentum induced transition from a deformed state of collective rotation to a noncollective configuration has been studied. In $^{158}$Er this transition manifests itself as favored band termination near extit{I}$approx$45$hbar$. The feeding of these band terminating states has been investigated for the first time using the GAMMASPHERE spectrometer. A large number of weakly populated states, lying at high excitation energy, that decay into these special states have been discovered. Cranked NilssonStrutinsky calculations suggest that these states arise from weakly collective configurations that break the $Z$=64 semimagic core. Additionally, a new frontier of discreteline $gamma$ray spectroscopy at ultrahigh spin has been opened in the rareearth nucleus $^{158}$Er. Two rotational structures, displaying high moments of inertia, have been identified, which extend up to spin $sim$65$hbar$ and bypass the bandterminating states in these nuclei near extit{I}$sim$45$hbar$. Cranked NilssonStrutinsky calculations suggest that these structures arise from welldeformed triaxial configurations that lie in a valley of favored shell energy, which also includes the wellknown triaxial strongly deformed bands in $^{161167}$Lu. Overall, 182 (209) new transitions, including 10 new bands, were placed in the greatly augmented level scheme of $^{158}$Er, as a result of our work in this thesis. Four of the new bands are based on high$$ extit{K} quasiparticle excitations, which provide a stringent test of the Cranked Shell Model. This enables the investigation and interpretation of many different quasiparticle configurations from their alignment properties and band crossings systematics. Results on $^{158}$Er have been published in extit{Phys. Rev. Lett.} and extit{Phys. Scr.} Finally, a local experiment, using the FSU tandem accelerator and the FSU $gamma$ray detectors, was performed to investigate the oddodd nucleus $^{158}$Tb. Unfortunately, no new significant results on the latter were obtained except for the tentative assignment of a new, stronglycoupled, rotational structure.}
Show less  Date Issued
 2006
 Identifier
 FSU_migr_etd0687
 Format
 Thesis
 Title
 Physics and Applications of Semiconducting Binary Oxide Nanobelts FieldEffect Transistors.
 Creator

Cheng, Yi, Xiong, Peng, Van Molnár, Stephan, Dobrosavljevic, Vladimir, Reina, Laura, Chase, P. Bryant, Department of Physics, Florida State University
 Abstract/Description

Nanotechnology is a frontier area of scientific research that involves materials and devices with at least one dimension at or below 100 nm scale. The ability to rationally synthesize and characterize functional materials at the nanometer scale has opened up numerous opportunities for unprecedented progress in many fields of research including materials science, solid state physics, chemistry, biology and engineering, and particularly at the interface of these disciplines. Nanoscale solid...
Show moreNanotechnology is a frontier area of scientific research that involves materials and devices with at least one dimension at or below 100 nm scale. The ability to rationally synthesize and characterize functional materials at the nanometer scale has opened up numerous opportunities for unprecedented progress in many fields of research including materials science, solid state physics, chemistry, biology and engineering, and particularly at the interface of these disciplines. Nanoscale solidstate devices have found important applications in electronics and sensing, offering the potential for highdensity, lowpower, efficient devices with novel functionalities. Nanoscale materials also offer unique opportunities for interfacing with chemical and biological molecular systems for effective transduction of chemical reactions and biological interactions into measurable electrical, mechanical, optical, or magnetic signals. In this thesis, we perform a set of systematic studies on a group of binary oxide nanobelts, primarily to evaluate their performance in electronic device and chemical/biological sensor applications. These nanobelts, synthesized through a simple physical vapor deposition growth method under controlled conditions, have emerged as a class of powerful quasionedimentional nanomaterials with high purity, uniformity and crystallinity. The nanoscale rectangular crosssection, long lengths up to hundreds of micrometers, and large widthtothickness ratio make them a unique class of nanomaterials with "belt"like morphology. To study the electrical properties of individual nanobelts, and most importantly, to provide an effective platform for building nanobelt sensors, through photolithography and metallization we successfully define multiple electrical contacts onto a single nanobelt. The electrical transport properties of a single nanobelt are studied through measurement of the temperature dependence of the resistivity. The results reveal that the nanobelts act as doped semiconductors possibly due to atomic defects dopants from high levels of surface oxygen deficiency. To explore potential electronic device applications of the nanobelts, we construct fieldeffect transistors (FETs) based on individual semiconducting oxide (SnO2 and ZnO) nanobelts , using a backgated structure with a heavilydoped silicon wafer as the gate and a thin layer of silicon dioxide on top as the delectric. Simultaneous twoterminal and fourterminal measurements enable direct correlation of the FET characteristics with the nature of the contacts. Devices with highresistance nonOhmic contacts exhibit Schottky barrier FET behavior. In contrast, lowresistance Ohmic contacts on the nanobelt lead to highperformance nchannel depletion mode FETs with welldefined linear and saturation regimes, large "on" current, and an on/off ratio as high as 107. The excellent intrinsic characteristics of these nanobelt FETs make them ideal candidates as nanoscale biological and chemical sensors based on fieldeffect modulation of the channel conductance. SnO2 nanobelt FETs with lowresistance Ohmic contacts are characterized as room temperature hydrogen gas sensors. The mechanism for the hydrogen sensing is determined to be the change of the oxygen stoichiometric state of the SnO2 nanobelt surface in the presence of H2. The advantages of these sensors include high sensitivity, short response time, low operating temperature, and low power consumption. Using the same setup and measurements, the important physical parameters such as resistivity, effective carrier concentration, and mobility of the nanobelts are determined from measurements of the transistors' IV characteristics in varying concentrations of ambient oxygen. Intrinsic channellimited SnO2 nanobelt FETs are shown to operate as excellent insolution pH sensors as well, owing to the conductance responses to the surface hydroxyl groups undergoing protonation and deprotonation. Integration of microfluidics and passivation of the electrodes are incorporated for the insolution sensing. Detailed sensor responses to pH and ion concentration, and the effect of surface molecular modification are characterized. The nanosensor conductance response to the surface electrical field caused by positively charged hydrogen ions and the electrostatic screening effect are discussed in detail. The insolution pH sensing with SnO2 nanobelt FETs have laid much of the groundwork towards the realization of biosensing. By working with the oxide surface chemistry and controlled organic molecular assembly, we successfully achieve selective nanoscale manipulation on the tin oxide surface with amino silane. This leads to the covalent surface linkage of a Bcomplex vitamin of interest, biotin. Biotinfunctionalized tin oxide nanobelt FET device is characterized as a protein sensor. The specific protein detected is streptavidin, which has high specific binding affinity to biotin. As the streptavidin molecules bind to the biotin on the nanobelt surface, their charges induce local electrostatic gating of the FET channel and a change in its conductance. The electrical detection is corroborated by fluorescence from the quantum dot tags on the streptavidin. Moreover, since the protein charging level is pH dependent, the effect is expected to vary with the solution pH; this effect is demonstrated and the results provide useful guidelines in optimizing the protein detection sensitivity. The detection of a biomedically significant biomolecule using this platform is demonstrated through the sensing of cTnI, one of the protein markers as reliable early indicators of cardiac damage from a cardiac arrest. The successful experiment is realized by functionalizing the nanobelt surface with the cTnI antibody through the biotinstretavidin linkage. The binding of the cTnI antigen results in a change in the FET channel conductance, which exhibits the expected pH dependence. Control experiments on an unmodified tin oxide nanobelt are performed and no significant conductance response is observed. The results provide a powerful proof of concept for the nano FETs as viable devices for ultrasensitive, highly specific, labelfree, and most importantly, portable realtime biomedical sensors. They also showcase the great promise of the nanobelt FET platform in particular, and the combination of surface molecular assembly with nanoscale solid state electronics in general, in basic studies of biomolecular interactions and in novel biomedical applications.
Show less  Date Issued
 2009
 Identifier
 FSU_migr_etd3826
 Format
 Thesis
 Title
 NexttoLeadingOrder Corrections to Weak Boson Production with a Massive Quark Jet Pair at Hadron Colliders.
 Creator

Febres Cordero, Fernando, Reina, Laura, Aluﬃ, Paolo, Baer, Howard, Prosper, Harrison, Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

We present the calculation of NexttoLeadingOrder Quantum Chromo Dynamics corrections for the production of W or Z weak bosons associated with a bottom antibottom quark pair at hadron colliders (ppbar, pp to W/Z bbbar), including the effects of a nonzero bottomquark mass. We find a considerable reduction of the renormalization and factorization scale dependence of our results with respect to LeadingOrder calculations. In particular, we study the impact of the corrections on the total...
Show moreWe present the calculation of NexttoLeadingOrder Quantum Chromo Dynamics corrections for the production of W or Z weak bosons associated with a bottom antibottom quark pair at hadron colliders (ppbar, pp to W/Z bbbar), including the effects of a nonzero bottomquark mass. We find a considerable reduction of the renormalization and factorization scale dependence of our results with respect to LeadingOrder calculations. In particular, we study the impact of the corrections on the total cross section and invariant mass distributions of the bottom antibottom quark pair at the Fermilab Tevatron ppbar collider. We perform a detailed comparison with a calculation that considers massless bottom quarks and find significant deviations in regions of phase space with small invariant mass of the bottom antibottom quark pair. Our results will be relevant to ongoing and future searches at hadron colliders, as the W/Z bbbar production mode is the main background to important signals, such as light Standard Model Higgs boson production or single topquark production.
Show less  Date Issued
 2007
 Identifier
 FSU_migr_etd4486
 Format
 Thesis
 Title
 Yukawa Unification in SO(10) Susy Guts.
 Creator

Auto, Daniel M., Baer, Howard, Hunter, Christopher, Reina, Laura, Prosper, Harrison, Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

Supersymmetric grand unified models based on the SO(10) gauge group are especially attractive in light of recent data on neutrino masses. The simplest SO(10) SUSY GUT models predict unification of third generation Yukawa couplings (t –b – Ƭ) in addition to the usual gauge coupling unification. An assessment of the viability of such Yukawa unified models is presented. For the superpotential Higgs mass parameter μ>0, it is found that unification to less than 1% is possible, but only for GUT...
Show moreSupersymmetric grand unified models based on the SO(10) gauge group are especially attractive in light of recent data on neutrino masses. The simplest SO(10) SUSY GUT models predict unification of third generation Yukawa couplings (t –b – Ƭ) in addition to the usual gauge coupling unification. An assessment of the viability of such Yukawa unified models is presented. For the superpotential Higgs mass parameter μ>0, it is found that unification to less than 1% is possible, but only for GUT scale scalar mass parameter m16 ~ 8 – 20 TeV, and small values of gaugino mass m1/2 ≤ 150 GeV. Such models require tha a GUT scale mass splitting exists amongst Higgs scalars with m2Hu < m2Hd. Viable solutions lead to a radiatively generated inverted scalar mass hierarchy, with third generation and Higgs scalars being lighter than other sfermions. These models have a very heavy sfermions, so that unwanted flavor changing and CP violating SUSY processes are suppressed, but may suffer from some finetuning requirements. While the generated spectra satisify b → sγ and (g – 2)μ constraints, there exists tension with the dark matter relic density unless m16 ≤ 3TeV. These models offer prospects for SUSY discovery at the Fermilab Tevatron collider via the search for W1Z2 → 3l events, or via gluino pair production. If μ < 0, Yujawa coupling unification to less than 5% can occur for m16 and m 1/2≥ 1 – 2 TeV. Consistency of negative μ Yukawa unified models with b → sγ, (g – 2)μ, and relic density Ωh2 all imply very large values of m1/2 typically greater than about 2.5 TeV, in which case direct dection of sparticles may be a challenge even at the LHC. To address the tension between Yukawa unification and the excess of dark matter that the μ>0 models tend to predict, a couple of possible improvements are surveyed. One solution lowering the GUT scale mass value of first and second generation scalars, leads to uR and cR squark masses in the 90 – 120 GeV regime, which should be accessible to Fermilab Tavatron experiments. Another possibility is relaxing gaugino mass universality which may solve the relic density problem by having neutralino annihilations via the Z or h resonances, or by having a winolike LSP.
Show less  Date Issued
 2004
 Identifier
 FSU_migr_etd0037
 Format
 Thesis
 Title
 Exotic Nuclei and Relativistic MeanField Theory.
 Creator

Rutel, Bonnie Gwen, Piekarewicz, Jorge, Capstick, Simon, Cottle, Paul, Reina, Laura, Kopriva, David A., Department of Physics, Florida State University
 Abstract/Description

A relativistic meanfield model is used to study the groundstate properties of neutronrich nuclei. Nonlinear isoscalarisovector terms, unconstrained by present day phenomenology, are added to the model Lagrangian in order to modify the poorly known density dependence of the symmetry energy. These new terms soften the symmetry energy and reshape the theoretical neutron drip line without compromising the agreement with existing groundstate information. A strong correlation between the...
Show moreA relativistic meanfield model is used to study the groundstate properties of neutronrich nuclei. Nonlinear isoscalarisovector terms, unconstrained by present day phenomenology, are added to the model Lagrangian in order to modify the poorly known density dependence of the symmetry energy. These new terms soften the symmetry energy and reshape the theoretical neutron drip line without compromising the agreement with existing groundstate information. A strong correlation between the neutron radius of Pb208 and the binding energy of valence orbitals is found: the smaller the neutron radius of Pb208, the weaker the binding energy of the last occupied neutron orbital. Thus, models with the softest symmetry energy are the first ones to drip neutrons. Further, in anticipation of the upcoming onepercent measurement of the neutron radius of Pb208 at the Thomas Jefferson Laboratory, a close relationship between the neutron radius of Pb208 and neutron radii of elements of relevance to atomic parityviolating experiments is established. On the basis of relativistic mean field calculations, we demonstrate that the spinorbit splitting of p3/2 and p1/2 neutron orbits depends sensitively on the magnitude of the proton density near the center of the nucleus, and in particular on the occupation of s1/2 proton orbits. We focus on two exotic nuclei, Ar46 and Hg206, in which the presence of a pair of s1/2 proton holes would cause the spinorbit splitting between the p3/2 and p1/2 neutron orbits near the Fermi surface to be much smaller than in the nearby doublymagic nuclei Ca48 and Pb208. We also explore how partial occupancy of the s1/2 proton orbits affects this quenching. We note that these two exotic nuclei depart from the longstanding paradigm of a central potential proportional to the ground state baryon density and a spinorbit potential proportional to the derivative of the central potential.
Show less  Date Issued
 2004
 Identifier
 FSU_migr_etd1956
 Format
 Thesis
 Title
 High Precision Atomic Mass Spectrometry with Applications to Neutrino Physics, Fundamental Cosntants and Physical Chemistry.
 Creator

Mount, Brianna, Myers, Edmund, Bonesteel, Nicholas, Marshall, Alan, Reina, Laura, Wiedenhoever, Ingo, Department of Physics, Florida State University
 Abstract/Description

The Florida State University singleion cryogenic Penning trap mass spectrometer has been used to precisely measure the masses of the doublets 76Ge/76Se and 74Ge/74Se to provide precision Qvalues to aid in searches for neutrinoless double beta decay as well as neutrinoless double electron capture. The observation of these processes would provide evidence for the Majorana nature of the electron neutrino and information on neutrino mass. The smallest known âdecay Qvalue has also been...
Show moreThe Florida State University singleion cryogenic Penning trap mass spectrometer has been used to precisely measure the masses of the doublets 76Ge/76Se and 74Ge/74Se to provide precision Qvalues to aid in searches for neutrinoless double beta decay as well as neutrinoless double electron capture. The observation of these processes would provide evidence for the Majorana nature of the electron neutrino and information on neutrino mass. The smallest known âdecay Qvalue has also been determined by the measurement of the masses of 115In and 115Sn. The masses of stable alkali isotopes for application as precision mass references as well as for the photonrecoil method of determining the fine structure constant have also been measured. For physical chemistry, the masses of the oxygen isotopes, 17O and 18O have been measured to test the DunhamWatson formalism for the rovibrational energy levels of isotopic variants of a diatomic molecule. By measuring the small shifts in cyclotron frequency due to polarizability, the dipole moments of NH+ and the astrophysically important molecule HCO+ have been measured for the first time. The mass of 19F has also been measured for use as a mass standard. Several improvements and developments to the FSU Precision Penning Trap (FSUPPT) have enabled these measurements. A vapor loader now allows vapors to be introduced into the trap, greatly increasing the range of species that can be measured. The previously developed technique for measuring a cyclotron frequency ratio, in which two ions are simultaneously trapped, but swapped between large and small cyclotron orbits has been further developed to allow the ion in the large cyclotron orbit to be constantly monitored and therefore recentered more efficiently. This technique has also been extended to enable twoion cyclotron frequency ratio measurements of nonmass doublets, as well as of multiply charged ions.
Show less  Date Issued
 2010
 Identifier
 FSU_migr_etd2217
 Format
 Thesis
 Title
 Phenomenology of Supergravity Models with NonUniversal Scalar Masses.
 Creator

Mustafayev, Azar, Baer, Howard, Aldrovandi, Ettore, Reina, Laura, Wahl, Horst D., Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

Supersymmetry (SUSY) is one of the most compelling theoretical extensions of the Standard Model. Many physicists believe that the discovery of SUSY may be imminent and that current and upcoming experiments will finally be able to observe it. Because of the large number of parameters and limited information about physics at very high energy, one should combine all available experimental results with cosmological date in order to determine viable models. One of the major unknowns in SUSY is the...
Show moreSupersymmetry (SUSY) is one of the most compelling theoretical extensions of the Standard Model. Many physicists believe that the discovery of SUSY may be imminent and that current and upcoming experiments will finally be able to observe it. Because of the large number of parameters and limited information about physics at very high energy, one should combine all available experimental results with cosmological date in order to determine viable models. One of the major unknowns in SUSY is the origin and pattern of the supersymmetry breaking scalar masses. For the sake of simplicity, they are usually taken to be universal at the grand unification (GUT) scale. In this study, we discuss theoretical motivations for scalar mass nonuniversality and explore its experimental signatures. We show that the seemingly innocuous deviation from universality in scalar masses can significantly alter our expectations in terms of dark matter as well as (s)particle physics phenomenology. This dissertation is devoted to the analysis of scalar mass nonuniversality in supergravity models and consists of two parts. After a brief review of phenomenology of models with universality, in the first part, we relax universality of scalar mass terms between generations at GUT scale. This should be done with great care  breaking generational universality of the GUTscale soft masses induces flavorviolating processes at the weak scale. We find that recent constraints from b →sγ, (g −2)μ and relic density of neutralino Dark Matter can be simultaneously satisfied if one makes the third generation scalar masses heavier than the degenerate first and second generation scalar masses. This scenario has light sleptons that yield large rates for multilepton processes that, as we have shown in our study, make it testable at the LHC, LC and possibly at the Tevatron. In the second part, we have examined the possibility that the soft SUSY breaking mass parameters in the Higgs sector are unrelated to the matter scalar masses mo. We conducted extensive investigation of one and two parameter models of this type. Previously it was known that making Higgs mass squared parameters independent of mo and positive can lower relic density for almost any mSUGRA point. In this study we have found for the first time the particular correlation of Higgs mass squared parameters with other SUSY parameters and experimental observables in the viable parameter space. For example, we have found that allowing Higgs mass squared parameters to take negative values can decrease the axial Higgs boson mass to the Afunnel (2mZ1 mA) with a neutralino relic density in accord with WMAP results even at low tanβ. This wasn't possible for positive Higgs mass squared parameters. We also study implications of these models for Dark Matter detection experiments and collider searches.
Show less  Date Issued
 2006
 Identifier
 FSU_migr_etd2158
 Format
 Thesis
 Title
 Evidence for Single Top Quark Production Using Bayesian Neural Networks.
 Creator

Kau, Daekwang, Prosper, Harrison B., Aldrovandi, Ettore, Adams, Todd, Reina, Laura, Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

We present results of a search for single top quark production in pp collisions using a dataset of approximately 1 fb−1 collected with the DØ detector. This analysis considers the muon+jets and electron+jets final states and makes use of Bayesian neural networks to separate the expected signals from backgrounds. The observed excess is associated with a pvalue of 0.081%, assuming the backgroundonly hypothesis, which corresponds to an excess over background of 3.2 standard deviations for a...
Show moreWe present results of a search for single top quark production in pp collisions using a dataset of approximately 1 fb−1 collected with the DØ detector. This analysis considers the muon+jets and electron+jets final states and makes use of Bayesian neural networks to separate the expected signals from backgrounds. The observed excess is associated with a pvalue of 0.081%, assuming the backgroundonly hypothesis, which corresponds to an excess over background of 3.2 standard deviations for a Gaussian density. The pvalue computed using the SM signal cross section of 2.9 pb is 1.6%, corresponding to an expected significance of 2.2 standard deviations. Assuming the observed excess is due to single top production, we measure a single top quark production cross section of _(p¯p ! tb+X, tqb+X) = 4.4±1.5 pb.
Show less  Date Issued
 2007
 Identifier
 FSU_migr_etd3296
 Format
 Thesis
 Title
 A Model for ππ and πη Photoproduction.
 Creator

Kiswandhi, Alvin Stanza, Capstick, Simon, Aldrovandi, Ettore, Piekarewicz, Jorge, Reina, Laura, Eugenio, Paul, Department of Physics, Florida State University
 Abstract/Description

We describe a model of general twototwobody and twotothreebody hadronic reaction based on a phenomenological Lagrangian approach that satisfies twobody unitary and is relativistic. This model is used to study πη photoproduction. Unitarity is ensured by using the LippmannSchwinger equation to iterate the vertices and dress the propagators to all orders, and by including all possible twobody and quasitwobody intermediate channels. We also study different approximations of the...
Show moreWe describe a model of general twototwobody and twotothreebody hadronic reaction based on a phenomenological Lagrangian approach that satisfies twobody unitary and is relativistic. This model is used to study πη photoproduction. Unitarity is ensured by using the LippmannSchwinger equation to iterate the vertices and dress the propagators to all orders, and by including all possible twobody and quasitwobody intermediate channels. We also study different approximations of the intermediate momenta in a diagram. Gauge invariance is used as a criterion to choose the best approximation. This model has been tested by investigating the nonresonant interactions of ππ and πη photoproduction, in which significant effects are observed. A preliminary comparison of our calculation to an existing πη photoproduction study is made, and is shown to produce consistent results.
Show less  Date Issued
 2008
 Identifier
 FSU_migr_etd2826
 Format
 Thesis
 Title
 Electron Tunneling Transport Across Heterojunctions Between Europium Sulfide and Indium Arsenide.
 Creator

Kallaher, Raymond L., Van Molnár, Stephan, Strouse, Geoffrey, Xiong, Peng, Bonesteel, Nicholas, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

This dissertation presents research done on utilizing the ferromagnetic semiconductor europium sulfide (EuS) to inject spin polarized electrons into the nonmagnetic semiconductor indium arsenide (InAs). There is great interest in expanding the functionality of modern day electronic circuits by creating devices that depend not only on the flow of charge in the device, but also on the transport of spin through the device. Within this mindset, there is a concerted effort to establish an...
Show moreThis dissertation presents research done on utilizing the ferromagnetic semiconductor europium sulfide (EuS) to inject spin polarized electrons into the nonmagnetic semiconductor indium arsenide (InAs). There is great interest in expanding the functionality of modern day electronic circuits by creating devices that depend not only on the flow of charge in the device, but also on the transport of spin through the device. Within this mindset, there is a concerted effort to establish an efficient means of injecting and detecting spin polarized electrons in a two dimensional electron system (2DES) as the first step in developing a spin based field effect transistor. Thus, the research presented in this thesis has focused on the feasibility of using EuS, in direct electrical contact with InAs, as a spin injecting electrode into an InAs 2DES. Doped EuS is a concentrated ferromagnetic semiconductor, whose conduction band undergoes a giant Zeeman splitting when the material becomes ferromagnetic. The concomitant difference in energy between the spinup and spindown energy bands makes the itinerant electrons in EuS highly spin polarized. Thus, in principle, EuS is a good candidate to be used as an injector of spin polarized electrons into nonmagnetic materials. In addition, the ability to adjust the conductivity of EuS by varying the doping level in the material makes EuS particularly suited for injecting spins into nonmagnetic semiconductors and 2DES. For this research, thin films of EuS have been grown via ebeam evaporation of EuS powder. This growth technique produces EuS films that are sulfur deficient; these sulfur vacancies act as intrinsic electron donors and the resulting EuS films behave like heavily doped ferromagnetic semiconductors. The growth parameters and deposition procedures were varied and optimized in order to fabricate films that have minimal crystalline defects. Various properties and characteristics of these EuS films were measured and compared to those characteristics found in previous reported work on doped EuS crystals. In particular, the magnetic switching behavior of individual microfabricated EuS structures was investigated to determine what types of spintronic devices EuS is best suited for. These studies found that the crystalline anisotropy of EuS dominates the switching behavior in EuS thin film structures with minimum feature sizes greater than ~ 5 ìm. This, in conjunction with the relatively high resistance of junctions between EuS and semiconductors, restricts the use of two tandem EuS electrodes in all semiconductor spintronic devices that require independently switching ferromagnetic electrodes. Spin transport studies in InAs 2DES are particularly interesting because of the heterostructure's high electron mobility and tunable spinorbit interactions.Detailed measurements of the electrical transport characteristics across the heterojunction formed between EuS and InAs were taken in order to investigate the spin transport characteristics across the junction. These measurements show that the electrical transport across the heterojunction, below the ferromagnetic transition temperature, is directly related to the magnetization of the EuS layer and thus the transport is dominated by the spindependent Schottky barrier formed in EuS. Using a simple theory developed for these junctions, the magnitude of the change in barrier height – half the Zeeman splitting of the conduction band in EuS – was found to be ~0.22 eV. The electrical transport measurements of the heterojunction between EuS and InAs at temperatures well above the ferromagnetic transition temperature of EuS shows that there are at least two separate scattering mechanisms in these junctions. As expected, critical scattering is the dominate scattering mechanism in the strongly paramagnetic regime; however, unexpectedly, the data show that critical scattering is not the dominate mechanism at temperatures greater than ~ 100 K. The high temperature electrical transport measurements of the EuS / InAs heterojunction, in conjunction with low temperature zerobias conductance measurements on junctions between EuS and gold (Au), suggest that there exists an interfacial layer in series with the magnetic Schottky barrier in these EuS junctions. This interfacial layer is modeled and explained as resulting from a rather high concentration of defects at the interface between EuS and the counter electrode.
Show less  Date Issued
 2007
 Identifier
 FSU_migr_etd3361
 Format
 Thesis
 Title
 Intersection Numbers of Divisors in Graph Varieties.
 Creator

Jones, Deborah, Aluffi, Paolo, Aldrovandi, Ettore, Hironaka., Eriko, Klassen, Eric, Reina, Laura, Department of Mathematics, Florida State University
 Abstract/Description

This dissertation studies certain intersection numbers of exceptional divisions arising from blowing up subspaces of lattices associated to graphs. These permit the computation of the Segre class of a scheme associated to the graph/lattice. Explicit formulas are provided for lattices associated to trees and several patterns among these numbers are explored. The problem can be related to the study of socalled Cremona transformations. It is shown that the geometry of such transformations...
Show moreThis dissertation studies certain intersection numbers of exceptional divisions arising from blowing up subspaces of lattices associated to graphs. These permit the computation of the Segre class of a scheme associated to the graph/lattice. Explicit formulas are provided for lattices associated to trees and several patterns among these numbers are explored. The problem can be related to the study of socalled Cremona transformations. It is shown that the geometry of such transformations explain a certain symmetry pattern we discovered.
Show less  Date Issued
 2003
 Identifier
 FSU_migr_etd3426
 Format
 Thesis
 Title
 Threshold Resummation in Direct Photon Production.
 Creator

Sato, Nobuo, Owens, Joseph Francis, Aldrovandi, Ettore, Reina, Laura, Prosper, Harrison, Schlottmann, Pedro, Department of Physics, Florida State University
 Abstract/Description

In this work, we study the phenomenology of direct photon production using theoretical predictions at nexttoleading order with threshold resummation up to nexttoleading logarithmic accuracy . By analyzing the global data sets of direct photons, we have found a good agreement between the theory and the data for a wide range of energies (√s = 23 GeV up to 7 TeV) if we exclude the data from E706 experiment. We have study the potential impact of direct photon data on parton distribution...
Show moreIn this work, we study the phenomenology of direct photon production using theoretical predictions at nexttoleading order with threshold resummation up to nexttoleading logarithmic accuracy . By analyzing the global data sets of direct photons, we have found a good agreement between the theory and the data for a wide range of energies (√s = 23 GeV up to 7 TeV) if we exclude the data from E706 experiment. We have study the potential impact of direct photon data on parton distribution functions using Bayesian reweighting approach. A reduction of 10% around 0.3 < x < 0.6 is observed in the uncertainties of the gluon distribution.
Show less  Date Issued
 2014
 Identifier
 FSU_migr_etd9085
 Format
 Thesis
 Title
 Braiding and Berry's Phases in NonAbelian Quantum Hall States.
 Creator

Zikos, Georgios, Bonesteel, Nicholas, Aldrovandi, Ettore, Schlottmann, Pedro, Reina, Laura, Chiorescu, Irinel, Department of Physics, Florida State University
 Abstract/Description

If one could be built, a quantum computer would be capable of storing and manipulating quantum states with sufficient accuracy to carry out computations that no classical computer can do (most notably factoring integers in polynomial time). The greatest obstacle to building such a device is the problem of error and decoherence. Classical computers can exploit the physical robustness of ordered states to protect classical information (as in, for example, the magnetically ordered state of a...
Show moreIf one could be built, a quantum computer would be capable of storing and manipulating quantum states with sufficient accuracy to carry out computations that no classical computer can do (most notably factoring integers in polynomial time). The greatest obstacle to building such a device is the problem of error and decoherence. Classical computers can exploit the physical robustness of ordered states to protect classical information (as in, for example, the magnetically ordered state of a hard drive). Remarkably, a type of quantum order known as topological order can, in principle, play the same role for quantum information. The best studied topologically ordered states are quantum Hall states. These states arise when a twodimensional electron gas is placed in a strong magnetic field and cooled to low temperatures. Under the right conditions, the electrons condense into an incompressible quantum liquid whose excitations are particlelike objects with fractional charge (quasiparticles). Certain quantum Hall states are thought to be non Abelian. This means that when a finite number of quasiparticles are present and fixed in space there is a low energy Hilbert space with finite dimension, rather than a unique state. Unitary operations can then be carried out on this Hilbert space by adiabatically dragging quasiparticles around one another so that their worldlines sweep out braids in 2+1 dimensional space time. A quantum computer which stores quantum information in this Hilbert space and computes by braiding is known as a topological quantum computer. In this thesis I review our work on determining precisely how one would carry out a computation on a topological quantum computer. I focus on the socalled Fibonacci anyonsquasiparticles which may exist in the experimentally observed quantum Hall state at Landau level filling fraction ν = 12/5. I give explicit prescriptions for encoding qubits (quantum bits) using Fibonacci anyons, and show how one would carry out a universal set of quantum gates (the quantum analogs of Boolean logic gates) by braiding them. I then focus in particular on my work developing algorithms for performing brute force searches over the space of braids to find braids which produce unitary operations close to any desired operation. These brute force searches are a crucial part of our quantum gate construction, and I show that by using a socalled "load balanced" bidirectional search I can find braids which approximate any desired operation to an accuracy of 1 part in 10 5 . I then turn to my work calculating the Berry's phase obtained when quasiparticles are moved around one another in the MooreRead state, a non Abelian state generally believed to describe the ν = 5/2 quantum Hall effect. This work is done using variational Monte Carlo, a method which allows one to numerically evaluate the Berry's phase for finite size systems. By exploiting certain properties of the MooreRead state I have been able to study systems consisting of as many as 150 electrons. In so doing I have verified the conjectured connection between the Berry's phase produced by physically moving quasiparticles around one another and the mathematical phase one obtains by simply analytically continuing the quasiparticle coordinates. An added benefit of these calculations is that we can deduce the length scale which determines the size of the quasiparticles. This length scale dictates how far apart the quasiparticles must be in order to prevent errors when they are used for topological quantum computation.
Show less  Date Issued
 2009
 Identifier
 FSU_migr_etd0503
 Format
 Thesis
 Title
 Supersymmetry at pp¯, pp and e+e− Colliders in Light of Wmap Measurements of the Dark Matter Density of the Universe.
 Creator

Krupovnickas, Tadas, Baer, Howard, Aldrovandi, Ettore, Reina, Laura, Adams, Todd, Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

The Standard Model (SM) describes almost all the particle physics experiments with a high accuracy. However, the SM has a lot of conceptual problems (spontaneous symmetry breaking is introduced by hand, the Higgs boson mass has to be very finely finetuned, there is no explanation for the number of generations or particle quantum numbers, there are at least 19 arbitrary model parameters). Therefore, it is reasonable to search for theories solving some or all of the problems that the SM has....
Show moreThe Standard Model (SM) describes almost all the particle physics experiments with a high accuracy. However, the SM has a lot of conceptual problems (spontaneous symmetry breaking is introduced by hand, the Higgs boson mass has to be very finely finetuned, there is no explanation for the number of generations or particle quantum numbers, there are at least 19 arbitrary model parameters). Therefore, it is reasonable to search for theories solving some or all of the problems that the SM has. One class of such theories is based on an assumption that at some large energy scale Nature chooses the maximal possible spacetime symmetry, called supersymmetry (SUSY). Once the theory is constructed, it has to be tested against the experiment. This dissertation explores various collider signals in the framework of minimal Supergravity model (mSUGRA) and gaugino mediated SUSY breaking model (inoMSB). We calculate whether the signal predicted by these models could be detected at the Fermilab Tevatron and at the CERN LHC hadronic colliders, and also explore the capabilities of a future electronpositron Linear Collider. We show the collider reach contours in the mSUGRA parameter space, combined with constraints from other experiments. We also devise new cuts, optimizing the signal to background ratio in the regions where no such work was previously done.
Show less  Date Issued
 2004
 Identifier
 FSU_migr_etd2897
 Format
 Thesis
 Title
 The Deconfining Phase Transition in and out of Equilibrium.
 Creator

Bazavov, Oleksiy, Berg, Bernd A., Mascagni, Michael, Capstick, Simon, Frawley, Anthony, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

Recent experiments carried out at the Relativistic Heavy Ion Collider at the Brookhaven National Laboratory provide strong evidence that a matter can be driven from a confined, lowtemperature phase, observed in our every day world into a deconfined hightemperature phase of liberated quarks and gluons. The equilibrium and dynamical properties of the deconfining phase transition are thus of great theoretical interest, since they also provide an information about the first femtoseconds of the...
Show moreRecent experiments carried out at the Relativistic Heavy Ion Collider at the Brookhaven National Laboratory provide strong evidence that a matter can be driven from a confined, lowtemperature phase, observed in our every day world into a deconfined hightemperature phase of liberated quarks and gluons. The equilibrium and dynamical properties of the deconfining phase transition are thus of great theoretical interest, since they also provide an information about the first femtoseconds of the evolution of our Universe, when the hot primordial soup while cooling has undergone a chain of phase transitions. The aspects of the deconfining phase transition studied in this work include: the dynamics of the SU(3) gauge theory after the heating quench (which models rapid heating in the heavyion collisions), equilibrium properties of the phase transition in the SU(3) gauge theory with boundaries at low temperature (small volumes at RHIC suggest that boundary effects cannot be neglected and periodic boundary conditions normally used in lattice simulations do not correspond to the experimental situation), and a study of the order of the transition in U(1) gauge theory.
Show less  Date Issued
 2007
 Identifier
 FSU_migr_etd1166
 Format
 Thesis
 Title
 Direct Photon Production in Association with a Heavy Quark.
 Creator

Stavreva, Tzvetalina P., Owens, Joseph F., Dewar, William, Reina, Laura, Wahl, Horst, Fenley, Marcia, Department of Physics, Florida State University
 Abstract/Description

In this Thesis we present the NextToLeadingOrder calculation, O(ααs2), of the inclusive cross section for a photon and a heavy quark (charm or bottom), p bar p / pp γ + Q +X, (Q=c,b) at hadron colliders. We include fragmentation effects through the NextToLeadingOrder. This calculation is performed with the use of a phase space slicing technique so that the effects of experimental cuts can be easily included. We study in detail the characteristics of this process at both the Tevatron and...
Show moreIn this Thesis we present the NextToLeadingOrder calculation, O(ααs2), of the inclusive cross section for a photon and a heavy quark (charm or bottom), p bar p / pp γ + Q +X, (Q=c,b) at hadron colliders. We include fragmentation effects through the NextToLeadingOrder. This calculation is performed with the use of a phase space slicing technique so that the effects of experimental cuts can be easily included. We study in detail the characteristics of this process at both the Tevatron and the LHC. Results for the ratios of the charm and bottom cross sections are presented and the systematics of the various subprocesses are compared and contrasted. The theory predictions are compared to experimental measurements from the DO collaboration at Fermilab. A brief overview of the LO massive calculation is also presented, and compared to the NLO massless case. We predict that the investigation of this process and our results will be relevant in the study of heavy quark PDFs at the LHC.
Show less  Date Issued
 2009
 Identifier
 FSU_migr_etd1572
 Format
 Thesis
 Title
 ZSum Approach to Loop Integrals.
 Creator

Rottmann, Paulo A., Reina, Laura, Aluﬃ, Paolo, Berg, Bernd A., Wahl, Horst D., Rikvold, Per Arne, Department of Physics, Florida State University
 Abstract/Description

We study the applicability of the ZSum approach to multiloop calculations with massive particles in perturbative quantum field theory. We systematically analyze the case of oneloop scalar integrals, which represent the building blocks of any higherloop calculation. We focus in particular on triangle oneloop integrals and identify strengths and limitations of the ZSum approach, extending our results to the case of oneloop box integrals when appropriate. We conclude with the calculation...
Show moreWe study the applicability of the ZSum approach to multiloop calculations with massive particles in perturbative quantum field theory. We systematically analyze the case of oneloop scalar integrals, which represent the building blocks of any higherloop calculation. We focus in particular on triangle oneloop integrals and identify strengths and limitations of the ZSum approach, extending our results to the case of oneloop box integrals when appropriate. We conclude with the calculation of a specific physical example: the calculation of heavy flavor corrections to the renormalized scattering amplitude for deep inelastic scattering.
Show less  Date Issued
 2011
 Identifier
 FSU_migr_etd1784
 Format
 Thesis
 Title
 Physics of Compact Stars.
 Creator

Taruna, Jutri, Piekarewicz, Jorge, Aldrovandi, Ettore, Capstick, Simon, Eugenio, Paul, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

This thesis starts with a pedagogical introduction to the study of white dwarfs and neutron stars. We will present a stepbystep study of compact stars in hydrostatic equilibrium leading to the equations of stellar structure. Through the use of a simple finitedifference algorithm, solutions to the equations for stellar structure both for white dwarfs and neutron stars are presented. While doing so, we will also introduce the physics of the equation of state and insights on dealing with...
Show moreThis thesis starts with a pedagogical introduction to the study of white dwarfs and neutron stars. We will present a stepbystep study of compact stars in hydrostatic equilibrium leading to the equations of stellar structure. Through the use of a simple finitedifference algorithm, solutions to the equations for stellar structure both for white dwarfs and neutron stars are presented. While doing so, we will also introduce the physics of the equation of state and insights on dealing with units and rescaling the equations. The next project consists of the development of a 'semiclassical' model to describe the equation of state of neutronrich matter in the 'Coulomb frustrated' phase known as nuclear pasta. In recent simulations we have resorted to a classical model that, while simple, captures the essential physics of the nuclear pasta, which consists of the interplay between long range Coulomb repulsion and short range nuclear attraction. However, for the nuclear pasta the de Broglie wavelength is comparable to the average interparticle separation. Therefore, fermionic correlations are expected to become important. In an effort to address this challenge, a fictitious 'Pauli potential' is introduced to mimic the fermionic correlations. In this thesis we will examine two issues. First, we will address some of the inherent difficulties in a widely used version of the Pauli potential. Second, we will refine the potential in a manner consistent with the most basic properties of a degenerate free Fermi gas, such as its momentum distribution and its twobody correlation function. With the newly refined potential, we study various physical observables, such as the twobody correlation function via Metropolis MonteCarlo simulations.
Show less  Date Issued
 2008
 Identifier
 FSU_migr_etd1687
 Format
 Thesis
 Title
 Exotic Smoothness, Branched Covering Spaces, Andquantum Gravity.
 Creator

Duston, Christopher Levi, Marcolli, Matilde, Reina, Laura, Klassen, Eric, Prosper, Harrison, Vafek, Oskar, Aldrovandi, Ettore, Hironaka, Eriko, Department of Physics, Florida...
Show moreDuston, Christopher Levi, Marcolli, Matilde, Reina, Laura, Klassen, Eric, Prosper, Harrison, Vafek, Oskar, Aldrovandi, Ettore, Hironaka, Eriko, Department of Physics, Florida State University
Show less  Abstract/Description

This thesis addresses the role of topology and geometry in quantum gravity. A major topic will be how inequivalent differentiable structures (exotic smoothness) can play a physically significant role in both semiclassical gravity and loop quantum gravity. We will discuss the result of including these structures into a physical theory, and describe some approaches to fully account for them. We will also be able to use our construction to study the topology of loop quantum gravity. In our...
Show moreThis thesis addresses the role of topology and geometry in quantum gravity. A major topic will be how inequivalent differentiable structures (exotic smoothness) can play a physically significant role in both semiclassical gravity and loop quantum gravity. We will discuss the result of including these structures into a physical theory, and describe some approaches to fully account for them. We will also be able to use our construction to study the topology of loop quantum gravity. In our framework, topology change will be a natural part of the theory. The approaches discussed in this thesis will be inspired by novel mathematical results, applied to established physical models. It is hoped that the methods described herein will lead to a greater understanding of the deep connection between geometry and physics, particularly as it relates to the geometrical nature of the gravitational field.
Show less  Date Issued
 2013
 Identifier
 FSU_migr_etd7363
 Format
 Thesis
 Title
 A GammaRay Spectroscopy Study for Higher Spin Structure of ³¹Si.
 Creator

Tai, PeiLuan, Tabor, Samuel Lynn, Humayun, Munir, Riley, Mark A., Volya, Alexander, Reina, Laura, Florida State University, College of Arts and Sciences, Department of Physics
 Abstract/Description

This work presents a comprehensive gammaray spectroscopic study to the higher spin structure of ³¹Si, including its excitation energies, spins, and branching ratios, along with the shell model discussions. ³¹Si was produced through the ¹⁸O(¹⁸O, alpha n) reaction at the beam energy of 25 MeV, which preferentially populates the higher spin states. The alpha particles from the reaction were detected in the Microball detector and the multiple gammaray coincidences were detected by GAMMASPHERE....
Show moreThis work presents a comprehensive gammaray spectroscopic study to the higher spin structure of ³¹Si, including its excitation energies, spins, and branching ratios, along with the shell model discussions. ³¹Si was produced through the ¹⁸O(¹⁸O, alpha n) reaction at the beam energy of 25 MeV, which preferentially populates the higher spin states. The alpha particles from the reaction were detected in the Microball detector and the multiple gammaray coincidences were detected by GAMMASPHERE. The ³¹Si recoil energies and angles were eventbyevent kinematically reconstructed by using the information of the energies and angles of the alpha evaporations detected by Microball. The kinematic correction led to a better Doppler correction and allowed us to discover 26 new states and 49 newlyobserved gamma transitions in total. 15 gammadecaying states above the neutron separation energy were identified, and two highest gammadecaying states are at the energies 9323 and 9216keV. Spin and parity assignments are based on gammaray angular distribution analysis, DCO ratios analysis, branching ratio, and shell model predictions. For the positiveparity states predicted by the shell model calculations using USDA and WBPa interactions agree well with the measured ones. But for the crossshell states, the shell model calculations have RMS around 400500 keV based on testing the lowest three measured negative parity states.
Show less  Date Issued
 2016
 Identifier
 FSU_2016SU_Tai_fsu_0071E_13321
 Format
 Thesis
 Title
 Magnetothermal Transport and Elastoresistive Properties of LowDimensional Magnetoelectrics and Dichalcogenides.
 Creator

Benjamin, Shermane Mark, Choi, Eun Sang, Manousakis, Efstratios, Oates, William, Reina, Laura, Beekman, Christianne, Florida State University, College of Arts and Sciences,...
Show moreBenjamin, Shermane Mark, Choi, Eun Sang, Manousakis, Efstratios, Oates, William, Reina, Laura, Beekman, Christianne, Florida State University, College of Arts and Sciences, Department of Physics
Show less  Abstract/Description

Co₄Nb₂O₉ is a quasi two dimensional material that has been known to exhibit magnetoelectric behavior with an antiferromagnetic transition (T[subscript N]) at ∼ 27 K. Our findings reveal strong evidence of magnon heat transport below T[subscript N] through magnetothermal conductivity measurements. Magnetothermal coupling is strongest below 2 K around 0.2 T suggesting presence of the thermal heatvalve effect causing an increase in its thermal conductivity by nearly 4fold. Independent of field...
Show moreCo₄Nb₂O₉ is a quasi two dimensional material that has been known to exhibit magnetoelectric behavior with an antiferromagnetic transition (T[subscript N]) at ∼ 27 K. Our findings reveal strong evidence of magnon heat transport below T[subscript N] through magnetothermal conductivity measurements. Magnetothermal coupling is strongest below 2 K around 0.2 T suggesting presence of the thermal heatvalve effect causing an increase in its thermal conductivity by nearly 4fold. Independent of field, we not only see the presence of phononmagnon resonant scattering but also strong phononspin coupling; giving rise to an anisotropic thermal conductivity where within the plane of spins conductivity is greater than interplane. Thermal measurements were also carried out on Ba₃Cr₂O₈ which has been shown to undergo BoseEinstein condensation of magnetic excitations. Through intercalation with copper and palladium atoms between the layers of the transition metal dichalcogenides titanium diselenide (TiSe₂), it has previously been shown that where the intrinsic charge density wave’s (CDW) temperature dependent resistivity peak anomaly occurs (T[subscript cdw] ∼165 K) decreases with increased intercalation and/or hydrostatic pressure. To mimic the chemical pressure caused by intercalation, uniaxial physical pressure (both compression and expansion) is used along with the Poisson effect. In the experiment with compressive pressure perpendicular to the layers (caxis), resistivity data shows a shift in the peak (T[subscript cdw]) towards lower temperatures; expected for increasing dimensionality. For uniaxial pressure parallel to the layers, the Poisson effect should separate the layers, providing a separation of the layers similar to that of intercalation. Preliminary results show T[subscript cdw] increases initially, and then decreases. A prototype to induce uniaxial tension perpendicular to the layers has recently been developed and preliminary results will be reported. Electrical transport measurements were also executed for the first time on the first FE(II)TCNQ spin crossover (SCO) system ever synthesized. In fact, our material is the first structurally defined magnetically bistable semiconductor to be constructed from TCNQ radical ions. With the aid of spider silk fibers (detailed in further sections), our findings show it is a narrow bandgap semiconductor where its activation energy changes from 110 meV to 10 meV as it crosses the SCO transition temperature to lower temperature.
Show less  Date Issued
 2016
 Identifier
 FSU_FA2016_Benjamin_fsu_0071E_13618
 Format
 Thesis
 Title
 Automated OneLoop QCD and Electroweak Calculations with NLOX.
 Creator

Honeywell, Steven Joseph, Reina, Laura, Aluffi, Paolo, Owens, Joseph F., Roberts, Winston, Yohay, Rachel, Florida State University, College of Arts and Sciences, Department of...
Show moreHoneywell, Steven Joseph, Reina, Laura, Aluffi, Paolo, Owens, Joseph F., Roberts, Winston, Yohay, Rachel, Florida State University, College of Arts and Sciences, Department of Physics
Show less  Abstract/Description

We introduce a new framework, NLOX, in which oneloop QCD and electroweak corrections to Standard Model processes can be automatically calculated. Within this framework, we calculate the first order of electroweak corrections to the hadronic production of Z + 1bjet and discuss some of the most relevant theoretical issues related to this process.
 Date Issued
 2017
 Identifier
 FSU_2017SP_Honeywell_fsu_0071E_13868
 Format
 Thesis
 Title
 A Search for Supersymmetry with Two Photons and Missing Transverse Energy at CMS at a Center of Mass Energy of 13 TeV.
 Creator

Santra, Arka, Askew, Andrew, Tyson, Gary Scott, Adams, Todd, Reina, Laura, Piekarewicz, Jorge, Florida State University, College of Arts and Sciences, Department of Physics
 Abstract/Description

The present theoretical framework to describe the universe in particle level, the Standard Model describes only 4% of the matterenergy budget of the universe. There are many theories which attempt to describe the universe beyond the scope of the Standard Model. This dissertation describes a search for supersymmetry, a beyond Standard Model theory, using data collected by the Compact Muon Solenoid detector with integrated luminosity of 2.3 fb⁻¹ at a center of mass energy of 13 TeV during 2015...
Show moreThe present theoretical framework to describe the universe in particle level, the Standard Model describes only 4% of the matterenergy budget of the universe. There are many theories which attempt to describe the universe beyond the scope of the Standard Model. This dissertation describes a search for supersymmetry, a beyond Standard Model theory, using data collected by the Compact Muon Solenoid detector with integrated luminosity of 2.3 fb⁻¹ at a center of mass energy of 13 TeV during 2015. The data were produced in protonproton collisions at the Large Hadron Collider near Geneva, Switzerland. This search was performed with events having two photons and missing transverse energy in the final state. This final state was motivated by general gauge mediated supersymmetry breaking, one of the theories on how breaking of supersymmetry can be mediated. No significant excess over the expected background was observed. The result was interpreted with simplified model scans and 95% upper limit on production cross sections are provided.
Show less  Date Issued
 2016
 Identifier
 FSU_2016SU_Santra_fsu_0071E_13394
 Format
 Thesis
 Title
 Periodic Pieces of PseudoAnosov Flows in Graph Manifolds.
 Creator

Waller, Russell L., Fenley, Sérgio Roberto, Reina, Laura, Hironaka, Eriko, Heil, Wolfgang H., Mio, Washington, Florida State University, College of Arts and Sciences, Department...
Show moreWaller, Russell L., Fenley, Sérgio Roberto, Reina, Laura, Hironaka, Eriko, Heil, Wolfgang H., Mio, Washington, Florida State University, College of Arts and Sciences, Department of Mathematics
Show less  Abstract/Description

Our work builds on that of Barbot and Fenley to generalize Bonatti and Langevin's famous construction of a graph manifold with pseudoAnosov flow in which all Seiftert fibered pieces of the torus decomposition are periodic. We provide infinitely many new examples of such graph manifolds, as well as a complete classification  up to Seifert invariant  in the case that each Seiftert fibered piece is orientable and the flow is Anosov. We further demonstrate that the singularities of the flow...
Show moreOur work builds on that of Barbot and Fenley to generalize Bonatti and Langevin's famous construction of a graph manifold with pseudoAnosov flow in which all Seiftert fibered pieces of the torus decomposition are periodic. We provide infinitely many new examples of such graph manifolds, as well as a complete classification  up to Seifert invariant  in the case that each Seiftert fibered piece is orientable and the flow is Anosov. We further demonstrate that the singularities of the flow are not rigid but can rather be "rearranged", or even removed, without affecting the ambient manifold. To build our graph manifolds and model the pseudoAnosov flows that they support, we define and construct combinatorial objects known as flow graphs. We study these flow graphs and the surfaces, called fat graphs (or ribbon graphs), that retract onto them. In particular, we study flow graphs with the additional conditions needed to generate pseudoAnosov flows from the combinatorial data that the flow graphs provide, and classify the surfaces that admit flow graphs with these additional requirements.
Show less  Date Issued
 2015
 Identifier
 FSU_migr_etd9479
 Format
 Thesis
 Title
 Threshold Resummation and the Determination of Parton Distribution Functions.
 Creator

Westmark, David, Owens, Joseph F., Aldrovandi, Ettore, Reina, Laura, Blessing, Susan K., Roberts, Winston, Florida State University, College of Arts and Sciences, Department of...
Show moreWestmark, David, Owens, Joseph F., Aldrovandi, Ettore, Reina, Laura, Blessing, Susan K., Roberts, Winston, Florida State University, College of Arts and Sciences, Department of Physics
Show less  Abstract/Description

Precise knowledge of parton distribution functions (PDFs) is necessary to the accurate calculation of QCD observables initiated by hadrons. The deep inelastic scattering (DIS) and lepton pair production (LPP) processes are primary sources of information on PDFs. Recent global fits for PDFs have used DIS data from the large Bjorken $x$, moderate $Q^{2}$ region. It is known that there are large logarithms in this kinematic region that can be resummed using threshold resummation techniques. The...
Show morePrecise knowledge of parton distribution functions (PDFs) is necessary to the accurate calculation of QCD observables initiated by hadrons. The deep inelastic scattering (DIS) and lepton pair production (LPP) processes are primary sources of information on PDFs. Recent global fits for PDFs have used DIS data from the large Bjorken $x$, moderate $Q^{2}$ region. It is known that there are large logarithms in this kinematic region that can be resummed using threshold resummation techniques. The purpose of this study is to investigate the effects of simultaneously including DIS and LPP threshold resummation in the determinations of PDFs. The analysis includes a study of the effects of the choice of resummation prescription and of current resummation methods used in the LPP rapidity and $x_{F}$ distributions. It is demonstrated theoretically and phenomenologically that the current resummation methods for such distributions are approximations that lose accuracy at high rapidities or $x_{F}$. The unapproximated resummation formalism is extended to the $\overline{\mathrm{MS}}$ scheme in the minimal and Borel prescriptions and used in conjunction with resummation in DIS to perform a global fit. The resultant PDF sets that correspond to two choices of resummation prescription are analyzed to determine the effect of threshold resummation on PDF fits and its theoretical uncertainties.
Show less  Date Issued
 2015
 Identifier
 FSU_migr_etd9485
 Format
 Thesis
 Title
 Semileptonic Decay of Heavy Baryons in a Constituent Quark Model.
 Creator

Pervin, Muslema, Capstick, Simon, Roberts, Winston, Hunter, Christopher, Piekarewicz, Jorge, Eugenio, Paul, Reina, Laura, Department of Physics, Florida State University
 Abstract/Description

The semileptonic decays of heavy baryons, ΛQ and ΩQ are treated in the framework of a constituent quark model. Both nonrelativistic and semirelativistic Hamiltonians are used to obtain the baryon wave functions from a fit to the spectra, and the wave functions are expanded in both the harmonic oscillator and Sturmian bases. The latter basis leads to form factors in which the kinematic dependence on the square of the momentum transfer (q2) is in the form of multipoles, and the resulting form...
Show moreThe semileptonic decays of heavy baryons, ΛQ and ΩQ are treated in the framework of a constituent quark model. Both nonrelativistic and semirelativistic Hamiltonians are used to obtain the baryon wave functions from a fit to the spectra, and the wave functions are expanded in both the harmonic oscillator and Sturmian bases. The latter basis leads to form factors in which the kinematic dependence on the square of the momentum transfer (q2) is in the form of multipoles, and the resulting form factors fall faster as a function of q2 in the available kinematic ranges. As a result, decay rates obtained in the two models using the Sturmian basis are significantly smaller than those obtained using the harmonic oscillator basis. In the case of the Λc, decay rates calculated using the Sturmian basis are closer to the experimentally reported rates. However, we find a semileptonic branching fraction for the Λc to decay to excited Λ* states of 11% to 19%, in contradiction with what is assumed in available experimental analyses. Our prediction for the Λb semileptonic decays is that decays to the ground state Λc provide a little less than 70% of the total semileptonic decay rate. For the decays Λb > Λ Λc, the analytic form factors we obtain satisfy the relations expected from heavyquark effective theory at the nonrecoil point, at leading and nexttoleading orders in the heavyquark expansion. In addition, some features of the heavyquark limit are shown to naturally persist as the mass of the heavy quark in the daughter baryon is decreased. For the case of ΩQ decays there are no experimentally determined rates. However, we find that our analytical and numerical results for the form factors and rates of ΩQ decays compare well with HQET predictions. Our results indicate a significant inelastic branching fraction for Ωb > Ω Ωc(*) decays, which is about 37% in all of our models. For Ωc > Ξ Ξ(*) decays the elastic fraction dominates (about 82%) but it does not saturate the decay.
Show less  Date Issued
 2005
 Identifier
 FSU_migr_etd1992
 Format
 Thesis
 Title
 Dark Matter Detection in Supersymmetric Models with NonUniversal Gaugino Masses.
 Creator

Park, EunKyung, Baer, Howard, Aldrovandi, Ettore, Reina, Laura, Prosper, Harrison, Volya, Alexander, Department of Physics, Florida State University
 Abstract/Description

SUSY is one of the most promising new physics ideas, and will soon be tested at high energy accelerators like the CERN LHC. Moreover SUSY provides a good candidate for cold dark matter (CDM). In this dissertation, we investigated phenomenology of SUSY models with nonuniversal gaugino masses (NUGM) at colliding experiments using event generators such as ISAJET and examined direct and indirect detection rates of relic neutralino CDM in the universe. The motivation of these models is that in...
Show moreSUSY is one of the most promising new physics ideas, and will soon be tested at high energy accelerators like the CERN LHC. Moreover SUSY provides a good candidate for cold dark matter (CDM). In this dissertation, we investigated phenomenology of SUSY models with nonuniversal gaugino masses (NUGM) at colliding experiments using event generators such as ISAJET and examined direct and indirect detection rates of relic neutralino CDM in the universe. The motivation of these models is that in most of mSUGRA parameter space, the relic density $Omega_{ z_1}h^2$ is considerably larger than the WMAP measurement, and it is well known that if nonuniversal gaugino masses are allowed, then qualitatively new possibilities arise that are not realized in the mSUGRA model. Our first NUGM attempt is to allow a mixed winobino lightest SUSY particle (LSP) by lowering $SU(2)$ gaugino mass $M_2$ at the weak scale from its mSUGRA value while keeping the hypercharge gaugino mass $M_1$ fixed ({it Mixed Wino Dark Matter}). In this model, winolike $ ilde{Z_1}$ with sufficiently low $M_2$ compared to $M_1$ enhances $ ilde{Z_1} ilde{Z_1} ightarrow W_{1}^{+} W_{1}^{}$ annihilations to reach the WMAP measured relic density. The second attempt is study on the NUGM model with different signs of $M_1$ and $M_2$ ({it BinoWino CoAnnihilation Scenario}). In this case, there is little mixing, so that $ ilde{Z_1}$ remains nearly a pure bino or a pure wino. By increasing $M_1 simeq M_2$, enhanced binowino coannihilation can achieve the relic neutralino abundance. The final attempt of NUGM models is lowering the $SU(3)$ gaugino mass to diminish the effect of the large top quark Yukawa coupling in the running of the higgs mass, so that the value of superpotential $mu$ parameter gets efficiently low to give rise to mixed higgsino dark matter ({it Mixed Higgsino Dark Matter}). Consequences of these NUGM model studies show us that relaxing universality of gaugino masses in SUSY models leads to enhanced direct and indirect dark matter detection rates and reduced $m_{ ilde{Z_2}}m_{ ilde{Z_1}}$ mass gap so that the LHC and ILC can distinguish each NUGM model from others. Finally, we found that models with welltempered neutralinos, where the composition of the neutralino is adjusted to give observed relic density, yield target cross sections which are detectable at proposed experiments.
Show less  Date Issued
 2007
 Identifier
 FSU_migr_etd2254
 Format
 Thesis
 Title
 Myrberg's Numerical Uniformization.
 Creator

Li, Xin, Seppälä, Mika, Van Hoeij, Mark, Reina, Laura, Nolder, Craig, Quine, J. R. (John R.), Florida State University, College of Arts and Sciences, Department of Mathematics
 Abstract/Description

In 1920, Myrberg [23] presented a method for the numerical uniformization of hyperelliptic curves. His ingenious method is based on iterating opening certain slots. He obtains the uniformization as a limit of such a process. Myrberg considered a central part of the process, the convergence of the sequence approximating the uniformizing mapping, as obvious. Later, Seppala [27] proved the convergence by normal family techniques. This work reviews the construction of Myrberg's [23], and the...
Show moreIn 1920, Myrberg [23] presented a method for the numerical uniformization of hyperelliptic curves. His ingenious method is based on iterating opening certain slots. He obtains the uniformization as a limit of such a process. Myrberg considered a central part of the process, the convergence of the sequence approximating the uniformizing mapping, as obvious. Later, Seppala [27] proved the convergence by normal family techniques. This work reviews the construction of Myrberg's [23], and the convergence results of Seppala's[27]. Then we extended this uniformization algorithm to hyperelliptic curves defined by polynomial with odd degree. The most important contribution of this work is providing an optimized iteration algorithm, since the original method cannot provide accurate approximation. In the end, we implemented this optimized algorithm to build an applet, MyrbergUniform, which offers fast computation of numerical uniformization.
Show less  Date Issued
 2015
 Identifier
 FSU_migr_etd9380
 Format
 Thesis
 Title
 Third Order AHypergeometric Functions.
 Creator

Xu, Wen, Hoeij, Mark van, Reina, Laura, Agashe, Amod S. (Amod Sadanand), Aldrovandi, Ettore, Aluffi, Paolo, Florida State University, College of Arts and Sciences, Department of...
Show moreXu, Wen, Hoeij, Mark van, Reina, Laura, Agashe, Amod S. (Amod Sadanand), Aldrovandi, Ettore, Aluffi, Paolo, Florida State University, College of Arts and Sciences, Department of Mathematics
Show less  Abstract/Description

To solve globally bounded order $3$ linear differential equations with rational function coefficients, this thesis introduces a partial $_3F_2$solver (Section~\ref{3F2 type solution}) and $F_1$solver (Chapter~\ref{F1 solver}), where $_3F_2$ is the hypergeometric function $_3F_2(a_1,a_2,a_3;b_1,b_2\,\,x)$ and $F_1$ is the Appell's $F_1(a,b_1,b_2,c\,\,x,y).$ To investigate the relations among order $3$ multivariate hypergeometric functions, this thesis presents two multivariate tools:...
Show moreTo solve globally bounded order $3$ linear differential equations with rational function coefficients, this thesis introduces a partial $_3F_2$solver (Section~\ref{3F2 type solution}) and $F_1$solver (Chapter~\ref{F1 solver}), where $_3F_2$ is the hypergeometric function $_3F_2(a_1,a_2,a_3;b_1,b_2\,\,x)$ and $F_1$ is the Appell's $F_1(a,b_1,b_2,c\,\,x,y).$ To investigate the relations among order $3$ multivariate hypergeometric functions, this thesis presents two multivariate tools: compute homomorphisms (Algorithm~\ref{hom}) of two $D$modules, where $D$ is a multivariate differential ring, and compute projective homomorphisms (Algorithm~\ref{algo ProjHom}) using the tensor product module and Algorithm~\ref{hom}. As an application, all irreducible order $2$ subsystems from reducible order $3$ systems turn out to come from Gauss hypergeometric function $_2F_1(a,b;c\,\,x)$ (Chapter~\ref{chapter applications}).
Show less  Date Issued
 2017
 Identifier
 FSU_FALL2017_XU_fsu_0071E_14234
 Format
 Thesis
 Title
 Measurement of the ¹⁷F(d,n)¹⁸Ne Reaction at RESOLUT.
 Creator

Kuvin, Sean A., Wiedenhöver, Ingo, Fuelberg, Henry E., Tabor, Samuel Lynn, Piekarewicz, Jorge, Reina, Laura, Florida State University, College of Arts and Sciences, Department...
Show moreKuvin, Sean A., Wiedenhöver, Ingo, Fuelberg, Henry E., Tabor, Samuel Lynn, Piekarewicz, Jorge, Reina, Laura, Florida State University, College of Arts and Sciences, Department of Physics
Show less  Abstract/Description

The ¹⁷F(p,γ)¹⁸Ne reaction plays an important role in various astrophysical processes. However, direct measurements of (p,γ) reactions involving radioactive nuclei will remain difficult even at cuttingedge facilities in the near future. As a result, there is a need to develop reliable alternative methods to obtain the relevant information for understanding these reactions. The (d,n) proton transfer reaction is wellsuited for studying the (p,γ) reaction due to the low Qvalue at the proton...
Show moreThe ¹⁷F(p,γ)¹⁸Ne reaction plays an important role in various astrophysical processes. However, direct measurements of (p,γ) reactions involving radioactive nuclei will remain difficult even at cuttingedge facilities in the near future. As a result, there is a need to develop reliable alternative methods to obtain the relevant information for understanding these reactions. The (d,n) proton transfer reaction is wellsuited for studying the (p,γ) reaction due to the low Qvalue at the proton threshold and the less complicated transfer mechanism when compared to similar transfer reactions. Because neutrons are neutral particles and thereby difficult to detect, very few attempts have been made to study the (d,n) reaction using radioactive ion beams. Here, I describe the development of a compact neutron detector array, RESONEUT, that is specialized for detecting the low energy neutrons from the (d,n) reaction in inverse kinematics. The efficiency properties of the detectors are characterized in a stablebeam test experiment by detecting the low energy neutrons from the ¹²C(d,n)¹³N reaction in inverse kinematics. The detectors are then used in a radioactive beam experiment studying the ¹⁷F(d,n)¹⁸Ne reaction at the RESOLUT facility. Our results confirm that the 3+ state at E[subscript R]ٖ = 599.8 keV is the lowest lying l=0 proton resonance and no additional states were observed. We have also succeeded in measuring the transfer spectroscopic factors of the 2₂+ bound state by detecting neutrons from the transfer reaction. The results are consistent with the spectroscopic factors measured from the mirror reaction, ¹⁷17O(d,p)¹⁸O, but inconsistent with the spectroscopic factors measured in the ¹⁷O(p,γ)¹⁸F reaction by Rolfs[Nucl. Phys. A217, 29 (1973)]. As a result, the direct capture contribution to the reaction rate, previously calculated by Garcia et. al[Phys. Rev. C43, 2012 (1991)] using spectroscopic factors from Rolfs, will need to be revised.
Show less  Date Issued
 2015
 Identifier
 FSU_2016SP_Kuvin_fsu_0071E_12993
 Format
 Thesis
 Title
 Search for Large Extra Dimensions via Single Photon Plus Missing Energy Final States at √S =1.96 TeV.
 Creator

Carrera, Edgar F. (Edgar Fernando), Gershtein, Yuri, Prosper, Harrison, Schatschneider, Chris, Reina, Laura, Rogachev, Grigory, Wahl, Horst, Department of Physics, Florida State...
Show moreCarrera, Edgar F. (Edgar Fernando), Gershtein, Yuri, Prosper, Harrison, Schatschneider, Chris, Reina, Laura, Rogachev, Grigory, Wahl, Horst, Department of Physics, Florida State University
Show less  Abstract/Description

This dissertation presents a search for large extra dimensions in the single photon plus missing transverse energy final states. We use a data sample of approximately 2.7fb⁻¹ of pp̄ collisions at√s= 1.96 TeV (recorded with the DØ detector) to investigate direct Kaluza Klein graviton production and set limits, at the 95% C.L., on the fundamental mass scale MD from 970 to 816 GeV for two to eight extra dimensions.
 Date Issued
 2009
 Identifier
 FSU_migr_etd4163
 Format
 Thesis
 Title
 Higgs Boson Production with Heavy Quarks at Hadron Colliders.
 Creator

Jackson, Christopher B., Reina, Laura, Bowers, Philip L., Owens, Joseph F., Prosper, Harrison B., Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

One of the remaining puzzles in particle physics is the origin of electroweak symmetry breaking. In the Standard Model (SM), a single doublet of complex scalar fields is responsible for breaking the SU(2)L × U(1)Y gauge symmetry, thus giving mass to the electroweak gauge bosons via the Higgs mechanism and to the fermions via Yukawa couplings. The remnant of the process is a yet to be discovered scalar particle, the Higgs boson (h). Current and future experiments at hadron colliders hold great...
Show moreOne of the remaining puzzles in particle physics is the origin of electroweak symmetry breaking. In the Standard Model (SM), a single doublet of complex scalar fields is responsible for breaking the SU(2)L × U(1)Y gauge symmetry, thus giving mass to the electroweak gauge bosons via the Higgs mechanism and to the fermions via Yukawa couplings. The remnant of the process is a yet to be discovered scalar particle, the Higgs boson (h). Current and future experiments at hadron colliders hold great promise. The Fermilab Tevatron protonantiproton (pp¯) collider, which is currently running, has the potential to discover a light Higgs boson with mass between 100 and 200 GeV. Starting in 2007, the CERN protonproton (pp) Large Hadron Collider (LHC) will be able to produce a Higgs boson over its full mass range (up to 1 TeV) through multiple processes. Of particular interest is the production of a Higgs boson in association with a pair of heavy quarks, pp¯(pp) Q¯ Qh, where Q can be either a top or a bottom quark. Indeed, the production of a Higgs boson with a pair of top quarks provides a very distinctive signal in hadronic collisions where background processes are formidable, and it will be instrumental in the discovery of a Higgs boson below about 130 GeV at the LHC. Also, since the Higgs boson is radiated from a top quark, this channel provides a unique opportunity to directly measure the top quark Yukawa coupling. On the other hand, the production of a Higgs boson with bottom quarks can be strongly enhanced in models of new physics beyond the SM, e.g. supersymmetric models. If this is the case, b¯bh production will play a crucial role at the Tevatron where it could provide the first signal of new physics. Given the prominent role that Higgs production with heavy quarks can play at hadron colliders, it becomes imperative to have precise theoretical predictions for total and diï¬erential cross sections. Hadronic cross sections are mainly aï¬ected by strong interaction eï¬ects which, at high energy, are described by perturbative Quantum Chromodynamics (QCD). Lowestorder predictions in perturbative QCD are often severely plagued by renormalization and factorization scale dependence. Therefore, to obtain precise results, it becomes mandatory to calculate cross sections beyond the LO. In this thesis, we report on the nexttoleading order (NLO) QCD calculation for the total and diï¬erential cross p(pp) Q ¯The sections of p¯Qh. NLO cross sections exhibit drastically reduced dependence on renormalization and factorization scales and, thus, lead to increased confidence in predictions based on these results. In fact, the results presented in this thesis are currently being used in experimental simulations at both the Tevatron and the LHC. In the first part of this thesis, we outline and present detailed results for the NLO QCD calculation of t¯ th production at both the Tevatron and the LHC. This calculation involves several difficult issues due to the three massive particles in the final state, a situation which is at the frontier of radiative correction calculations in quantum field theory. For instance, the virtual oneloop corrections contain pentagon Feynman diagrams with several massive internal and external particles that pose both analytic and numerical challenges. Another difficulty arises in the calculation of the real gluon emission contribution, where one must compute a fourbody phase space containing three massive particles. In this thesis, we will detail the novel techniques we have developed to deal with these challenges. In the second part of this thesis, we focus on the production of Higgs bosons with bottom quarks. The calculation of pp¯(pp) b¯bh at NLO in QCD involves several subtle issues not encountered in the case of pp¯(pp) –th. Both from t¯an experimental and theoretical standpoint, it is important to distinguish between inclusive and exclusive b¯bh production. In fact, the production of a Higgs boson with a pair of b quarks can be detected via: (i) a fully exclusive measurement, when both b jets are identified; (ii) a fully inclusive measurement, when no b jet is identified; or (iii)a semiinclusive measurement, when at least one of the two b jets is identified. Theoretically, diï¬erent calculational approaches may be adopted when a final state b quark is treated either exclusively or inclusively. In this thesis, we present results for both exclusive and inclusive production of Higgs bosons with bottom quarks, and we devote particular care to clarifying some outstanding issues concerning the inclusive production modes. Indeed, when a final state b quark is not identified, the corresponding integration over its phase space gives rise to large collinear logarithms originating from the region of low transverse momentum. These collinear logarithms appear at every order in the strong coupling ∂s and, hence, could hinder the convergence of the perturbative expansion. Currently, there are two approaches to the calculation of inclusive Higgs production with bottom quarks: one can (i) calculate the partonic processes gg, qq¯b¯bh at fixed order in ∂s with no special treatment of the collinear logarithms (the socalled Four Flavor Number Scheme) or (ii) introduce a bottom quark Parton Distribution Function, in which case the semiinclusive process becomes gb bh and the inclusive one b¯b h, and resum leading and subleading logarithms through the AltarelliParisi equation (the socalled Five Flavor Number Scheme). Here, we compare these two seemingly diï¬erent schemes and show that they produce compatible results for the total and diï¬erential cross sections in the cases of Higgs production with zero tagged b jets and one tagged b jet. This comparison is made possible by having computed the NLO QCD cross section for b¯bh production.
Show less  Date Issued
 2005
 Identifier
 FSU_migr_etd3556
 Format
 Thesis
 Title
 Measurement of the Top Mass in the AllJets Channel with the DØ Detector at the Fermilab Tevatron Collider.
 Creator

Connolly, Brian M., Wahl, Horst, Krishnamurti, Ruby, Prosper, Harrison B., Stewart, Chip, Reina, Laura, Piekarewicz, Jorge, Department of Physics, Florida State University
 Abstract/Description

We describe a measurement in the top quark mass in tt production where the final state is 6 or more jets, which is otherwise known as the alljets channel. The mass is extracted from 110.2 pb of data taken with the DØ detector at the Fermilab Tevatron from 199396.
 Date Issued
 2002
 Identifier
 FSU_migr_etd3462
 Format
 Thesis
 Title
 Sensitive Spin Detection Using an onChip SquidWaveguide Resonator.
 Creator

Yue, Guang, Chiorescu, Irinel, Dalal, Naresh S., Reina, Laura, Schlottmann, Pedro U., Xiong, Peng, Florida State University, College of Arts Sciences, Department of Physics
 Abstract/Description

Quantum computing gives novel way of computing using quantum mechanics, which furthers human knowledge and has exciting applications. Quantum systems with diluted spins such as rare earth ions hosted in single crystal, moleculebased magnets etc. are promising qubits candidates to form the basis of a quantum computer. High sensitivity measurement and coherent control of these spin systems are crucial for their practical usage as qubits. The microSQUID (directcurrent micrometersized...
Show moreQuantum computing gives novel way of computing using quantum mechanics, which furthers human knowledge and has exciting applications. Quantum systems with diluted spins such as rare earth ions hosted in single crystal, moleculebased magnets etc. are promising qubits candidates to form the basis of a quantum computer. High sensitivity measurement and coherent control of these spin systems are crucial for their practical usage as qubits. The microSQUID (directcurrent micrometersized Superconducting QUantum Interference Device) is capable to measure magnetization of spin system with high sensitivity. For example, the microSQUID technique can measure magnetic moments as small as several thousand μB as shown by the study of [W. Wernsdorfer, Supercond. Sci. Technol. 22, 064013 (2009)]. Here we develop a novel onchip setup that combines the microSQUID sensitivity with microwave excitation. Such setup can be used for electron spin resonance measurements or coherent control of spins utilizing the high sensitivity of microSQUID for signal detection. To build the setup, we studied the fabrication process of the microSQUID, which is made of weaklinked Josephson junctions. The SQUID as a detector is integrated on the same chip with a shorted coplanar waveguide, so that the microwave pulses can be applied through the waveguide to excite the sample for resonance measurements. The whole device is plasma etched from a thin (∼20nm) niobium film, so that the SQUID can work at in large inplane magnetic fields of several tesla. In addition, computer simulations are done to find the best design of the waveguide such that the microwave excitation field is sufficiently strong and uniformly applied to the sample. The magnetization curve of Mn₁₂ moleculebased magnet sample is measured to prove the proper working of the microSQUID. Electron spin resonance measurement is done on the setup for gadolinium ions diluted in a CaWO₄ single crystal. The measurement shows clear evidence of the resonance signal from the 1st transition of the gadolinium ions' energy levels, which shows the setup is successfully built. Due to the high sensitivity of microSQUID and the ability to concentrate microwave energy in small areas of the chip, this setup can detect signals from a small number of spins (10⁷) in a small volume (several μm³).
Show less  Date Issued
 2017
 Identifier
 FSU_SUMMER2017_Yue_fsu_0071E_13872
 Format
 Thesis
 Title
 Clustering in Light Nuclei with Configuration Interaction Approaches.
 Creator

Kravvaris, Konstantinos, Volya, Alexander, Kopriva, David A., Weidenhoever, Ingo Ludwing M., Capstick, Simon, Reina, Laura, Florida State University, College of Arts and...
Show moreKravvaris, Konstantinos, Volya, Alexander, Kopriva, David A., Weidenhoever, Ingo Ludwing M., Capstick, Simon, Reina, Laura, Florida State University, College of Arts and Sciences, Department of Physics
Show less  Abstract/Description

The formation of substructures within an atomic nucleus, appropriately termed nuclear clustering, is one of the core questions of nuclear manybody physics. In this thesis, we put forward a new method for the study of nuclear clustering relying on the completely microscopic Configuration Interaction approach. We construct reaction cluster channels in a Harmonic Oscillator manybody basis that respect the symmetries of the Hamiltonian, are fully antisymmetrized, and carry a separable and...
Show moreThe formation of substructures within an atomic nucleus, appropriately termed nuclear clustering, is one of the core questions of nuclear manybody physics. In this thesis, we put forward a new method for the study of nuclear clustering relying on the completely microscopic Configuration Interaction approach. We construct reaction cluster channels in a Harmonic Oscillator manybody basis that respect the symmetries of the Hamiltonian, are fully antisymmetrized, and carry a separable and controlled Center of Mass component. Such channels are then used to explore cluster signatures in Configuration Interaction manybody wavefunctions. The Resonating Group Method is then applied, utilizing the reaction channels as a basis to capture the essential cluster characteristics of the system. We investigate the emergence of nuclear clustering in 2α, 2α+n, 2α+2n and 3α systems using a No Core Shell Model approach from first principles, and traditional Shell Model studies of clustering in heavier nuclei.
Show less  Date Issued
 2018
 Identifier
 2018_Su_Kravvaris_fsu_0071E_14611
 Format
 Thesis