The Study Of Hadronic Decay Of Charmonium At BESⅢ And Photoproduction Of Four Photon Final State With GlueX

Heavy quarkonium(QQ)presents an ideal environment for testing the interplay be-tween perturbative and nonperturbative Quantum Chromodynamics(QCD).Hadronic decays between the heavy QQ states are particularly interesting.For charmonium states below the DD threshold,the hadronic transitions of the spin-singlet P-wave state hc(11P1)and the spin-triplet P-wave states χcJ(13PJ)are the best places to test the spin-spin interaction between heavy quarksBESⅢ which operating at the BEPCⅡ has accumulated the world largest data sample of 448.1 × 106 at the energy of ψ(3686)peak.We performed search for the hadronic transition hc→π+π-J/ψ viaψ(3686)→π+hc based on the ψ(3686)data No signals of the transition are observed,and the upper limit on the product branching fraction B(ψ(3686)→π0hc)B(hc→π+π-J/ψ)at the 90%confidence level is deter-mined to be 2.0 x 10-6.This is the most stringent upper limit to date.Neglecting the small phase space difference between the charged and neutral ππ modes and assuming isospin symmetry,we obtain B(hc→ππJ/ψ)<3.6 × 10-3(including charged and neutral modes)at the 90%C.L.It is noted that the measured branching fraction is smaller than the prediction by Yu-Ping Kuang et al.with one order in magnitude,but does not contradict the calculation of Pyungwon KoTo study the hadronic decay of χcJ we measured χcJ→K*0K*0(J=0,1,2)with 447.9 × 106ψ(3686)events.The dynamics are complicated due to he degree of freedom of the coupling patterns especially for χc2 decays.And we use the sideband to extract the huge backgrounds from the same final states.The branching fractions are determined to be(1.45±0.05)x 10-3,(9.43±0.28)x 10-4,and(2.89±0.04)x 10-3 for the χc0,χcn and χc2,respectively,where the uncertainties are statistical onlyThe large acceptance of the GlueX detector provides access to mesons that decay to multiple photons.A channel that is rich in physics potential is γ+p→p+4γFor example,the photo-production of π+π+/π0η can be used to study the properties of the f0(980)and a0(980)mesons,respectively,and help discriminate among models for scalars.In the thesis,we present results from our 4γ survey of the Spring 2016 dataset,with emphasis on decays to π0η.Physical quantities such as beam asymmetry and momentum transfer are measured for these two channels.We also perform moment analysis which can be used to extract partial waves and search for exotic particles in the future.In addition,we discuss backgrounds and reconstruction efficiency for upcoming GlueX measurements of the rare decay η→π0γγ,which will be used to search for a iepto-phobic B boson in the mass range 0.14-0.5 GeV/c2 via η→γ+B→γ+[π0γ].