The Study Of ψ(2S)→π~03(π~+π~-)and J/ψ→γ3(π~+π~-) In BESⅢ

After the discovery of J/ψ,many charmonium states were subsequently discovered,such asψ(2S),ηc,hc,etc..The study of charmonium decay is helpful to understand the various mechanisms of quantum chromo-dynamics(QCD).As a member of the charmonium family,only a few decay modes of hc are observed.We can be hunting and study to the new decay modes of hc with the ψ(2S)←π0hc.The QCD predicts the existence of new forms of hadrons,such as glueballs,hybrids,and multi-quark states.The J/ψ decays provide an ideal laboratory for study the new forms of hadrons and light hadrons spectrum.Used the ψ(2S)and J/ψ data collected by the BESIII detector,a search for new decay modes of hc,and the study new forms of hadrons are presented.Based on 447.9 × 106 ψ(2S)events collected by the BESIII detector,the decays of ψ(2S)→π0hc is studied via hc→3(π+π-).After the event selection and background study,no evident hc signal is observed in the 3(π+π-)invariant mass spectrum.At 90%confidence level,the upper limit of the branching ratio of hc→3(π+π-)is measured to be B(hc→3(π+π-))<2.89 × 10-3.Based on 10 × 109 J/ψ events collected by the BESⅢ detector,the decay of J/ψ→γ3(π+π-)is studied,we have confirmed the existence of asymmetric X(1840)structure in the 3(π+π-)invari-ant mass spectrum.Meanwhile a rapid descend near the pp mass threshold on the 3(π+π-)mass spectrum is observed.Two different parameterizations,a coherent sum of two Breit-Wigner am-plitudes and the flatte formula,were performed to fit the X(1840)structure.Both models provide reasonable descriptions of the data:(1)For the case of flatte parameterization,a fit yields a gpp2/g02=3.00±0.41 show the ratio of coupling strength of the pp channel to that of all other channels in X(1840)decays.Significance of this ratio being non-zero is about 17.2a.(2)Another parameterization is performed with a sum of two coherent Breit-Wigner functions.The mass,width and the branching ratio of the X(1840)and X(1880)are summarized in the Table below.The above results obtained from the two parameterizations indicate that a connection between X(1840)and pp mass threshold,which implies the existence of a particle with strong coupling to pp final states or a narrow state just below the pp mass threshold.