We report new measurements of the cross sections for the production of DD final states at theψ(3770)resonance.Our data sample consists of an integrated luminosity of 2.93 fb^(-1)of e~+e^-annihilation data produc...We report new measurements of the cross sections for the production of DD final states at theψ(3770)resonance.Our data sample consists of an integrated luminosity of 2.93 fb^(-1)of e~+e^-annihilation data produced by the BEPCⅡ collider and collected and analyzed with the BESⅢ detector.We exclusively reconstruct three D^0and six D~+hadronic decay modes and use the ratio of the yield of fully reconstructed DD events(“double tags”)to the yield of all reconstructed D or D mesons(“single tags”)to determine the number of D^0 D^0and D~+D^-events,benefiting from the cancellation of many systematic uncertainties.Combining these yields with an independent determination of the integrated luminosity of the data sample,we find the cross sections to beσ(e~+e^-→D^0D^0)=(3.615±0.010±0.038)nb andσ(e~+e^-→D~+D^-)=(2.830±0.011±0.026)nb,where the uncertainties are statistical and systematic,respectively.展开更多
Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e+e-→γχc,j (J =0, 1, 2...Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e+e-→γχc,j (J =0, 1, 2) and find evidence for e+e-→γχc1 and e+e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB(e+e-→γχc,j), as well as their upper limits at the 90% con dence level (C.L.) are determined at each center-of-mass energy.展开更多
基金Supported by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11235011,11335008,11425524,11625523,11635010)+8 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Program,the CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1332201,U1532257,U1532258)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CAS,National 1000 Talents Program of China,INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology,German Research Foundation DFG under Contracts Nos.Collaborative Research Center CRC 1044,FOR 2359Istituto Nazionale di Fisica Nucleare,Italy,Koninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Science and Technology fund,The Swedish Research Council,U.S.Department of Energy(DEFG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069)University of Groningen(Ru G)and the Helmholtzzentrum fuer Schwerionenforschung Gmb H(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘We report new measurements of the cross sections for the production of DD final states at theψ(3770)resonance.Our data sample consists of an integrated luminosity of 2.93 fb^(-1)of e~+e^-annihilation data produced by the BEPCⅡ collider and collected and analyzed with the BESⅢ detector.We exclusively reconstruct three D^0and six D~+hadronic decay modes and use the ratio of the yield of fully reconstructed DD events(“double tags”)to the yield of all reconstructed D or D mesons(“single tags”)to determine the number of D^0 D^0and D~+D^-events,benefiting from the cancellation of many systematic uncertainties.Combining these yields with an independent determination of the integrated luminosity of the data sample,we find the cross sections to beσ(e~+e^-→D^0D^0)=(3.615±0.010±0.038)nb andσ(e~+e^-→D~+D^-)=(2.830±0.011±0.026)nb,where the uncertainties are statistical and systematic,respectively.
基金Supported by National Key Basic Research Program of China(2015CB856700)Joint Funds of National Natural Science Foundation of China(11079008,11179007,U1232201,U1332201,U1232107)+7 种基金National Natural Science Foundation of China(NSFC)(10935007,11121092,11125525,11235011,11322544,11335008)Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Program,CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CAS,INPAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(Collaborative Research Center CRC-1044)Istituto Nazionale di Fisica Nucleare,Italy,Ministry of Development of Turkey(DPT2006K-120470)Russian Foundation for Basic Research(14-07-91152)U.S.Department of Energy(DE-FG02-04ER41291,DE-FG02-05ER41374,DE-FG02-94ER40823,DESC0010118)U.S.National Science Foundation,University of Groningen(RuG)and Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e+e-→γχc,j (J =0, 1, 2) and find evidence for e+e-→γχc1 and e+e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB(e+e-→γχc,j), as well as their upper limits at the 90% con dence level (C.L.) are determined at each center-of-mass energy.