Study Of E~+e~-??? Decay At BES?

The observation of ??2170?was first reported by the BABAR Collaboration in the initial-state^-radiation?ISR?process e⁺e^-??ISR??+?-.Its JPC is regarded as 1--and it is later confirmed by the BES collaboration and the Belle collaboration.Theoret-ical physicists had discussed the essence of??2170?,for example,regarding??2170?as ssg hybrid,33S1ss quarkonium,23D1ss quarkonium,??structure and so on.How to judge the correctness of theoretical calculations need experimental collaboration to provide more experimental results.e⁺e???process is the fundamental process to research strange quarkonium,because the contribution of?*is depressed by OZI rule.The theoretical calculation result??23D1ss????=0???ssg????=1.2???33S1ss????=21,so the research of??final state can distinguish different model for??2170?.Based on 2015 R-Scan data on BES?experiment ats^1/2=2.000Ge V-3.080GeV,we measure the dependence of??e⁺e^-????ons^1/2???K+K-and?????.We investigate and optimize the criteria of signal selection,use MC topology method and sideband method to investigate the contributions of background,choose the suitable fitting function of signal events and investigate the contributions to systematic uncer-tainties from all the sources.Compared with the initial radiative result from BABAR collaboration,our experimental precision is obviously improved.The result accords with BABAR's result at most energy points,except minor energy points.In the line^-shape of??e⁺e^-????,we do not observe obvious??2170?signal.