Search For X(3872)??X(3823) At BES? Experiment

In particle physics,in addition to the mesons composed of one quark plus one anti-quark and the baryons composed of three quarks or three anti-quarks,Quantum Chromodynamics also allows the existence of exotic hadrons such as glueballs,hybrid states,and multiquark states.So far,a large number of charmonium and charmonium-like states have been found in experiments.While some of these are good candidates for regular charmonia,the others cannot be explained as regular charmonia.We collectively refer to these candidate exotic states as XYZ particles.In the last two decades,many new charmonium-like states have been discovered above the DD threshold,such as,X(3872),X(3823),Y(4260),Zc(3900)±/0.Among them,X(3872)and X(3823)were both observed for the first time in the Belle experiment.So far,LHCb measured accurately the mass and width of X(3872),as well as quantum numbers.The decay modes discovered in experiments such as BaBar,Belle,LHCb include:D*0D0+c.c.,?+?-J/?,?J/?,//?J/???0?cJ?Theoretically,there are many interpretations for the internal structure of X(3872),such as the regular charmonium ?c1(2P)state,?c1(2P)and molecular state or tetraquark state.However,none of the theoretical models have been experimentally confirmed.Searching for new decay modes of X(3872)is a important way to study its properties and can provide key information on its internal structure.The regular charmonium ?c1 2P)can transit to 13D2 by emitting a photon.Theoretically,the non-relativistic potential model and the Godfrey-Isgur relativistic potential model have calculated the decay width of ?c1(2P)???(13D2),?(13D2)???c1(1P).This thesis uses the data samples collected by BES? in the e+e-collision energy(?)=4.18-4.3GeV to search for X(3872)??X(3823),no obvious signal was observed in the signal region of X(3872),and thus we give the ratio of the product branching fraction of X(3872)??X(3823),X(3823)???c1 to branching fraction of X(3872)??+?-J/? at the 90%confidence level,which is 0.15.Due to the large uncertainty in the measurement of X(3872)and X(3823).the upper limit we provide can not determine the correctness of the theoretical calculation of the partial decay width of ?c1(2P)???(13D2).In the future,the BES?,Belle ?,LHCb and other experiments will provide more and more precise studies on X(3 872).