Study Of ψ (2S) Hadronic Transitions To J/ψ At BES-Ⅲ

The Beijing Election-positron spectrometer (BESIII) is an updated magnetic spectrom eter working at the 3-4 GeV energy region, which is designed for studying the Tau-charn physic and searching for new physics. As a member of charmonium familly, theφ(2S) decays especially the hadronic transition betweenφ(2S) and J/φ, become an important laboratory to study the charmonium decay properties in high energy physics. It is exciting that BESII has accumulated the largesφ(2S) data sample of about 106 x 106 decays in the world, which is four times large of CLEO-c having. This sample will provide us a solid found laboratory to study the light hadrons and Charmonium decay properties.In particle physics, hadrons including mesons and baryons are composed of two quarks and three quarks in the naive quark model, respectively. The heavy hadrons formed from heavy quarks can be well described with the perturbative QCD (pQCD) theory due to the non-relativistic effects and the asymptotic freedom for heavy quarks, but properties of light hadrons are hardly described with the pQCD theory due to the non-perturbative effects Various phenomenological models are developed to describe non-perturbative effects. The precise measurement on the light hadron production and decays are helpful to understand the non-perturbrive properties and test these models. This study is focus on the measurement of the branching fractions ofφ(2S)â†'η(Ï€0) J/φand their ratio. The results will shed light on the light quark mass and the isospin violation effects.The paper will give a detailed description on the measurement on the branch-ing fractions forφ(2S)â†'Ï€0(γγ)J/φ(e+e-),φ(2S)â†'Ï€0(γγ)J/φ(μ+μ-),φ(2S)â†'η(γγ)J/φ(e+e-)å'ŒÏ†(2S)â†'η(γγ)J/φ(μ+μ-), and the uncertainty estimation is also given The measured branching fractions and their ration R are consistent with CLEO-c measure-ments. Due to the largeφ(2S) data sample used, the results are improved in the precision of statistical errors.