From 2011 to 2014, the BESIII experiment collected about 5 fb^-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon proce...From 2011 to 2014, the BESIII experiment collected about 5 fb^-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e＋e- →yma/Fsμ^＋μ^-, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.展开更多
From December 2011 to May 2014, about 5 fb^-1 of data were taken with the BESIII detector at center-of- mass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher excited charmonium s...From December 2011 to May 2014, about 5 fb^-1 of data were taken with the BESIII detector at center-of- mass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher excited charmonium states. The time-integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process.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
A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be（223.7±...A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be（223.7±1.4）×10^6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be（1086.9±6.0）×10^6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be（1310.6±7.0）×10^6, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.展开更多
基金Supported by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(11125525,11235011.11322544,11335008,11425524,Y61137005C)+7 种基金Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Program,CAS Center for Excellence in Particle Physics(CCEPP),Collaborative Innovation Center for Particles and Interactions(CICPI),Joint Large-Scale Scientific Facility Funds of NSFC and CAS(11179007,U1232201,U1332201),CAS(KJCX2-YW-N29,KJCX2-YWN45),100 Talents Program of CASNational 1000 Talents Program of China,INPACShanghai Key Laboratory for Particle Physics and Cosmology,German 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)Swedish Research Council,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 Helniholtzzentrum fuer Schwerionenforschung GmbH(GSI),DarmstadtWCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘From 2011 to 2014, the BESIII experiment collected about 5 fb^-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e＋e- →yma/Fsμ^＋μ^-, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking.
基金Supported by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11125525,11235011,11322544,11335008,11425524)+5 种基金Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Program,Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(11179007,U1232201,U1332201)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CAS,INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology,German Research Foundation DFG(Collaborative Research Center CRC-1044),Istituto Nazionale di Fisica Nucleare,ItalyMinistry 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 the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),Darmstadt and WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘From December 2011 to May 2014, about 5 fb^-1 of data were taken with the BESIII detector at center-of- mass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher excited charmonium states. The time-integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process.
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.
基金Supported by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(10805053,11125525,11175188,11235011,11322544,11335008,11425524)+15 种基金Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Collaborative Innovation Center for Particles and Interactions(CICPI)Joint Large-Scale Scientific Facility Funds of NSFC and CAS(11179007,U1232201,U1232107,U1332201)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CAS,INPACShanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(Collaborative Research Center CRC-1044)Istituto Nazionale di Fisica Nucleare,ItalyMinistry 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 FoundationUniversity of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),DarmstadtWCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be（223.7±1.4）×10^6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be（1086.9±6.0）×10^6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be（1310.6±7.0）×10^6, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.
