The Study Of J/??p(?)?~0 Decay Chain On BES?

Light Hadron physics plays an important role in the field of high-energy physics.The charmonium J/? observed experimentally in 1974 has opened up a wide range of researches for the light hadron spectrum,and the Beijing Electron-Positron Collider has produced a large number of J/? particles by collision and annihilation of electron-positron pairs near the 3.097 GeV energy point.The J/? decays is an advantageous place to study the light hadron spectrum.After the upgrading of Beijing Electronic-Positron Collider and Beijing Spectrometer,the world's largest experimental data of J/? was collected,which conduces to the study of Light Hadron spectrum strongly.After the Beijing Electronic-Positron Collider was upgraded,it collected 1.31 billion J/? events in 2009 and 2012.The research work in this paper is based on 1.31 billion J/? events collected by Beijing Spectrometer ?.The decay of J/??p(?)?~0 is studied in detail and the the branching ratio is measured in this analysis.Because of the large width of ?0 meson which reaches 150 MeV.It can not be described by the non-relativistic Breit-Wigner function.We must consider the momentum dependence and use the relativistic Breit-Wigner function to describe the?0 signal.Since ?0 and ? mesons have the same spin parity and similar masses,the ?0-? interference effect must be considered in the fitting of experimental data.which makes the analysis difficult.The contents of the physical analysis include the selection of the signal events,the analysis of the background,the fitting of the mass spectrum,the calculation of the branch ratio and the related systematical uncertainties.The final result is as follows:Br(J/??p(?)?~0)=(4.71± 0.05(stat)± 0.96(sys)×10-4The branching ratio of this decay channel is not given on the PDG.The previous PDG gave only an upper limit.This is the first time in the world that the decay of J/??p(?)?~0 was observed and the the corresponding branching ratio was measured.The systematic errors and statistical errors has been successfully calculated at the same time.