Study Of The Decay Processes ?(3686)???_cj??p(?) And H_c??⁰J/?

Charmonium is a bound state composed of a pair of positive and negative charm quarks.Charmonium physics is very important for understanding the properties of perturbative and nonperturbative quantum chromodynamics and for exploring the behavior of strong interaction in the perturbative-nonperturbative transition region.The theoretical calculations of quark models are very successful in describing the charmonium spectrum.In the past 40 years,charmonium have made great progress.With the discovery of ?c(2S)and hc in experiments,all the charmonium with the mass below the DD threshold have been observed.In the theoretical study of charmonium,potential models have successfully described the charmonium spectrum below the DD threshold,but there are still some deviations between experimental measurements and theoretical predictions,which need further study.In this paper,we study the decay processes of some charmonium.By using the helicity amplitude method,we derive the complete helicity amplitude formula of charmonium cascade decay processes ?(3686)???cJ??pp,and obtain the expression of joint angular distribution formula,which provides theoretical support for the helicity amplitude analysis of these processes in experiment,and makes the detection efficiency of these processes more accurate in experiment.This will help to extract the multipole amplitude contribution of the processes ?(3686)???cJ.test the color octet mechanism and understand the mechanism of helicity selection rule breaking.Using these formulas,we obtain the helicity amplitude parameters of the processes?c1,2?pp from the angle distribution parameters a measured in the experiment.Based on the world's largest data sample size of ?(3686)collected at BESIII experiment,the accuracy of the helicity amplitude parameters of the processes?(3686)???cJ??pp is estimated.In this paper,we also propose to measure the decay process hc??0J/? by using the data sample collected above 4 GeV at BESIII experiment and the hc is produced by the process e+e-??+?-hc.In this way,the huge background process ?(3686)??0?0J/? in ?(3686)data sample can be avoided and the clean signals can be ensured.Using the measured cross section curves of the process e+e-??+?-hc,we estimate the cross section values and radiative correction factors at each energy point,and then estimate how many signal events of the process hc??0J/? can be observed at BES?experiment for the different partial widths.We get that based on the current data sample of BES?,the meaningful physical results can be obtained by studying the process hc??0J/?,which will help to understand the properties of quantum chromodynamics,constrain the relevant theoretical models,and further promote the theoretical progress of charmonium.