Study Of Exotic Hadrons In J/ψ Decays At Particle Detectors

The particle collider and detector are large-scale scientific facility,which can record physical information such as tracks,momentum and energy.Quantum Chromodynamics（QCD）successfully describes strong interaction.Further,it does not exclude the existence of exotic hadron states such as gulball,quark-gluon hybirds,and multi-quark states.Search-ing for these hadrons is of great significance to test and develope QCD,and it remains an im-portant topic for theoretical and experimental research in frontiers.Our researches are based on the experimental data from J/ψdecay channels collected by the detector of BESⅢ.In this thesis we address the nature of the X（2370）resonance observed in the J/ψra-diative decays,discussing the possibility that it is a glueball.We calculate amplitudes of J/ψ→γK⁺K^-η^′,J/ψ→γK_SK_Sη^′,J/ψ→γπ⁺π^-η^′and J/ψ→γηηη^′by chiral effective Lagrangian.Through the amplitude analysis and measurements of experiment,the branching ratio of J/ψ→γX（2370）can be extracted directly.We also fit to the in-variant mass spectrum to check.We perform a simultaneous fit to K⁺K^-η^′,K_SK_Sη^′andπ⁺π^-η^′invariant mass distributions in the processes of J/ψradiative decays as well as the branching ratio of J/ψ→γK⁺K^-η^′,J/ψ→γK_SK_Sη^′and the upper limit of branch-ing ratio J/ψ→γηηη^′.We find that Br[J/ψ→γX（2370）]is（3.26±0.81）×10^-3or（2.53±0.61）×10^-3,which is much larger than the glueball production rate predicted by Lattice QCD or other phenomenology analysis.Hence,the X（2370）is not likely to be a glueball,but a conventional q（?） meason.It is also found that the mass and width of the X（2370）are determined to be M=2387.8±1.3 MeV andΓ=119.6±6.7 MeV.In this thesis,we also perform an analysis of J/ψ→Φπ⁺π^-η^′,measuring the branch-ing ratio of this decay channel and searching for X（1835）resonance.With 10 billion J/ψdata collected by the BESⅢ experiment,we do not find obvious signal for X（1835）in J/ψ→Φπ⁺π^-η^′invariant mass spectrum and the branching ratio of J/ψ→Φπ⁺π^-η^′decay channel is determined to be（1.344±0.036（stat）±0.158（syst））×10^-4.X（2370）and X（1835）is one of the physical targets for detector researches,our work provides calculation basis and guidance for the improvement of detector electronics and data processing systems,and is of significance for development of particle detector technology.