Observation of e⁺e^-→■-+c.c.

作者：麦迪娜M.N.AchasovP.AdlarsonM.AlbrechtR.AlibertiA.Amoroso安美儒安琪白旭红白羽O.BakinaR.BaldiniFerroliI.Balossino班勇V.BatozskayaD.BeckerK.BegzsurenN.BergerM.BertaniD.BettoniF.BianchiJ.BlomsA.BortoneI.BoykoR.A.BriereA.Brueggemann蔡浩蔡啸A.Calcaterra曹国富曹宁S.A.Cetin**帆常万玲G.Chelkov陈琛陈超陈刚陈和生陈玛丽陈申见陈少敏T.Chen陈旭荣X.T.Chen陈元柏陈卓俊成伟帅初晓G.CibinettoF.Cossio崔佳佳代洪亮代建平A.DbeyssiR.E.deBoerD.Dedovich邓子艳A.DenigI.DenysenkoM.DestefanisF.DeMori丁勇董静董燎原董明义董翔杜书先P.Egorov范玉兰方建房双世方文兴方易R.FarinelliL.FavaF.FeldbauerG.Felici封常青冯俊华KFischerM.FritschC.Fr

来源：Chinese Physics C, 2023, 47(04): 22-31.

• Multi-baryon channel
• hexaquark
• di-baryon states
• cross section measurement

Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢ detector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb-1, the process e+e-→■+ c.c. is observed for the first time with a statistical significance of 11.5σ. The average Born cross sections in the energy ranges of（4.160, 4.380） GeV,（4.400, 4.600） GeV and（4.610, 4.700） GeV are measured to be（21.5±5.7±1.2） fb,（46.3±10.6±2.5） fb and （59.0±9.4±3.2） fb, respectively, where the first uncertainties are statistical and the second are systematic. The line shapes of the ■ and ppπ- invariant mass spectra are consistent with phase space distributions, indicating that no hexaquark or di-baryon state is observed.