Search for New and Unusual Strangeonia in Photoproduction Using CLAS

We perform a survey of the ( proton K+ K− ), 3 charged track data taken by the CLAS detector for the HyCLAS experiment [1] during the g12 run-period at Jefferson Lab. We aim to study the strong decay amplitudes, partial widths and production channels of strangeonia from the CLAS g12 dataset. HyCLAS was motivated by the experimental results for gluonic hybrid meson candidates, theoretical Lattice QCD, and Flux-tube Model calculations and predictions. The experiment was designed and conducted to search and observe new forms of hadronic matter through photoproduction. Crucial among the various channels explored in HyCLAS are those for strangeonia, resonances such as φ(1680), φ3 (1850) and Y(2175) [2] decaying to φ η . A meson decay via φ η is the signature that unequivocally identifies a strangeonium (s ̄) state and is the main focus of this thesis. A strangeonium decay via φ η is considered the premier decay mode to cleanly establish the strangeonia spectrum [3]. This is due to negligible interference of the φ η decay mode with the non-strange n ̄ (n ∈ {u, d}) meson decay modes, on account of the fact that φ(1020) is an almost pure s ̄ vector meson and the η meson possesses a strong component of s ̄ in it as well. Another analysis explored was the φ π o decay channel, which is an exotic decay mode for a meson. Decay of an initial s ̄ meson via this channel is forbidden on account of the conservation of isotopic spin whereas the decay of a n ̄ via the φ π o decay mode is also forbidden by the Okubo - Zweig - Iizuka (OZI) rule. Thus, observation of a resonance decaying to φ π o will provide strong evidence of mesons beyond q q , probably of a gluonic excitation - q q g or a tetraquark state - q q q q [4]. A final state of proton, K + and K − is selected from the g12 dataset. An intermediate φ state is identified by its decay to K + K − . Using Energy-Momentum conservation, missing mass in an event is calculated. Depending on the analyses, suitable missing mass cuts for the missing η mass or the π o mass is implemented to identify the particular missing particle. Invariant mass for the φ and the missing η/π o system is reconstructed to observe possible resonances. γ p → p X → p φ [η/π o ] → p K + K − [η/π o ] The yield and the cross section for the photoproduction of φ η mesons off of protons is calculated for Eγ ∈ {4.40, 5.45} GeV/c2 using elliptical sideband subtraction. Upper and lower limits on the photoproduction cross section for possible strangeonium resonances and their subsequent decay via the φ η intermediate state are calculated using the FeldMan- Cousins approach with a 90% confidence interval limit. A partial wave analysis is also performed on the φ η intermediate state to explore for discernable resonances. The yield and the cross section for the photoproduction of φ mesons off of protons is calculated for Eγ ∈ {4.40, 5.45} GeV/c2 . Yield is estimated for the intermediate state φ π o and its invariant mass distributions analyzed for possible resonances. The ( proton K+ K− ) final state is also explored for the rare φ ω events and the yield for the channel is measured.