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
The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detec...The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics（equivalently, 3000 tons for geo-neutrino and supernova neutrino physics）, the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos,geo-neutrinos, supernova neutrinos, and dark matter.展开更多
The number of φ＇ events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×（1.00±0.81%）×10^6. The err...The number of φ＇ events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×（1.00±0.81%）×10^6. The error is systematic dominant; the statistical error is negligible.展开更多
The numbers of ψ（3686） events accumulated by the BESⅢ detector for the data taken during 2009 and 2012 are determined to be（107.0±0.8）×10^6 and（341.1±2.1）×10^6, respectively, by counting in...The numbers of ψ（3686） events accumulated by the BESⅢ detector for the data taken during 2009 and 2012 are determined to be（107.0±0.8）×10^6 and（341.1±2.1）×10^6, respectively, by counting inclusive hadronic events,where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ（3686） events for the two data taking periods is（448.1±2.9）×10^6.展开更多
By analyzing 2.93 fb-1 data collected at the center-of-mass energy v/S = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D＋- k0e＋ ve via k0-π0π0 - （8.59 &#...By analyzing 2.93 fb-1 data collected at the center-of-mass energy v/S = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D＋- k0e＋ ve via k0-π0π0 - （8.59 ± 0.14 ± 0.21）% using k0- k0-π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties..展开更多
By analyzing the large-angle Bhabha scattering events e^＋e^- → （γ）e^＋e^- and diphoton events e^＋^e- → （γ）γγ for the data sets collected at center-of-mass （c.m.） energies between 2.2324 and 4.5900 GeV （...By analyzing the large-angle Bhabha scattering events e^＋e^- → （γ）e^＋e^- and diphoton events e^＋^e- → （γ）γγ for the data sets collected at center-of-mass （c.m.） energies between 2.2324 and 4.5900 GeV （131 energy points in total） with the upgraded Beijing Spectrometer （BESIII） at the Beijing Electron-Positron Collider （BEPCII）, the integrated luminosities have been measured at the different c.m. energies, individually. The results are important inputs for the R value and J/ψ resonance parameter measurements.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
To investigate the nature of the Ψ（3770） resonance and to measure the cross section for e^＋e^-→DD, a cross-section scan data sample, distributed among 41 center-of-mass energy points from 3.73 to 3.89 GeV, was ta...To investigate the nature of the Ψ（3770） resonance and to measure the cross section for e^＋e^-→DD, a cross-section scan data sample, distributed among 41 center-of-mass energy points from 3.73 to 3.89 GeV, was taken with the BESIII detector operated at the BEPCII collider in the year 2010. By analyzing the large angle Bhabha scattering events, we measure the integrated luminosity of the data sample at each center-of-mass energy point. The total integrated luminosity of the data sample is 76.16±0.04±0.61 pb^-1, where the first uncertainty is statistical and the second systematic.展开更多
Data sets were collected with the BESⅢ detector at the BEPCⅡ collider at the center-of-mass energy of √s=3.650 GeV during May 2009 and at √s=3.773 GeV from January 2010 to May 2011. By analyzing the large angle Bh...Data sets were collected with the BESⅢ detector at the BEPCⅡ collider at the center-of-mass energy of √s=3.650 GeV during May 2009 and at √s=3.773 GeV from January 2010 to May 2011. By analyzing the large angle Bhabha scattering events, the integrated luminosities of the two data sets are measured to be （44.49±0.02±0.44） pb-1 and （2916.94±0.18±29.17） pb-1, respectively, where the first error is statistical and the second error is systematic.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
To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle ...To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle Bhabha scattering events,the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb-1,where the first uncertainty is statistical and the second one is systematic.In addition,the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV,where the first uncertainty is statistical and the second one is systematic.展开更多
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
We study the hadronic decays of ∧c+ to the final states ∑+η and ∑+η’,using an e+e-annihilation data sample of 567 pb-1 taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCⅡ collider....We study the hadronic decays of ∧c+ to the final states ∑+η and ∑+η’,using an e+e-annihilation data sample of 567 pb-1 taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCⅡ collider.We find evidence for the decays ∧c+→∑+η and ∑+η’ with statistical significance of 2.5σ and 3.2σ,respectively.Normalizing to the reference decays ∧c+→∑+π0 and ∑+ω,we obtain the ratios of the branching fractions■and ■to be 0.35±0.16±0.02 and 0.86±0.34±0.04,respectively.The upper limits at the 90% confidence level are set to be■and■.Using BESIII measurements of the branching fractions of the reference decays,we determine B（∧c+→∑+η）=（0.41±0.19±0.05）%（<0.68%）and B（∧c+→∑+η’）=（1.34±0.53 ±0.19）%（<1.9%）.Here,the first uncertainties are statistical and the second systematic.The obtained branching fraction of ∧c+→∑+η is consistent with the previous measurement,and the branching fraction of ∧c+→∑+η’ is measured for the first time.展开更多
Studies of e^+e~→D_s^+■^((*)0)K^-and the P-wave charmed-strange mesons are performed based on an e^+e^-collision data sample corresponding to an integrated luminosity of 567 pb^(-1) collected with the BESIII detecto...Studies of e^+e~→D_s^+■^((*)0)K^-and the P-wave charmed-strange mesons are performed based on an e^+e^-collision data sample corresponding to an integrated luminosity of 567 pb^(-1) collected with the BESIII detector at s^(1/2)=4.600 GeV. The processes of e^+e^-→D_s^+■^(*0)K^- and D_s^+■~0K^- are observed for the first time and are found to be dominated by the modes D_s^+D_(s1)(2536)^-and D_s^+D_(s2)~*(2573)^-, respectively. The Born cross sections are measured to be σ~B(e^+e^-→D_s^+■^(*0)K^-) =(10.1±2.3±0.8) pb and σ~B(e^+e^-→D_s^+■~0K^-) =(19.4±2.3± 1.6) pb, and the products of Born cross section and the decay branching fraction are measured to be σ~B(e^+e^-→D_s^+D_(s1)(2536)^-+c.c.)·B(D_(s1)(2536)^-→■^(*0)K^-)=(7.5±1.8±0.7) pb and σ~B(e^+e^-→D_s^+D_(s2)~*(2573)^-+ c.c.)·B(D_(s2)~*(2573)^-→■~0 K^-)=(19.7 ± 2.9 ±2.0) pb. For the D_(s1)(2536)^-and D_(s2)~*(2573)^-mesons, the masses and widths are measured to be M(D_(s1)(2536)^-)=(2537.7±0.5 ±3.1) MeV/c2, Γ(D_(s1)(2536)^-) =(1.7 ±1.2 ±0.6)MeV, and M(D_(s2)~*(2573)^-)=(2570.7±2.0 ±1.7) MeV/c^2, Γ(D_(s2)~*(2573)^-)=(17.2 ±3.6 ±1.1) MeV. The spin-parity of the D_(s2)~*(2573)^-meson is determined to be J^p= 2^+. In addition, the processes e^+e^-→D_s^+■^((*)0)K^-are searched for using the data samples taken at four(two) center-of-mass energies between 4.416(4.527) and 4.575 GeV, and upper limits at the 90% confidence level on the cross sections are determined.展开更多
The number of J/ψ events collected with the BES detector at the BEPC from June 12 to July 28, 2009 is determined to be （225.3 ± 2.8） × 10^ 6 using J/ψ→inclusive events, where the uncertainty is the syst...The number of J/ψ events collected with the BES detector at the BEPC from June 12 to July 28, 2009 is determined to be （225.3 ± 2.8） × 10^ 6 using J/ψ→inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.展开更多
We have derived a formula for the neutron radiative capture cross section in the framework of a statistical model approach to nuclear reactions. Based on this formula, new systematics are established between the （n, ...We have derived a formula for the neutron radiative capture cross section in the framework of a statistical model approach to nuclear reactions. Based on this formula, new systematics are established between the （n, y） reaction cross section and the energy level density of a compound nucleus or a relative neutron excess of an even-even target nucleus for neutron incident energy above the resonance region to MeV. Good agreement with experimental data suggests that this new systematical law is helpful to nalyze the experimental data.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 the National Natural Science Foundation of China(11235006,11475093,11135009,11375065,11505301,and11620101004)the Tsinghua University Initiative Scientific Research Program(20121088035,20131089288,and 20151080432)+3 种基金the Key Laboratory of Particle&Radiation Imaging(Tsinghua University)the CAS Center for Excellence in Particle Physics(CCEPP)U.S.National Science Foundation Grant PHY-1404311(Beacom)U.S.Department of Energy under contract DE-AC02-98CH10886(Yeh)
文摘The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics（equivalently, 3000 tons for geo-neutrino and supernova neutrino physics）, the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos,geo-neutrinos, supernova neutrinos, and dark matter.
基金Supported by Ministry of Science and Technology of China(2009CB825200)National Natural Science Foundation of China(NSFC)(10625524,10821063,10825524,10835001,10935007,11125525,10975143,10979058),Joint Funds of the National Natural Science Foundation of China(11079008,11179007)+5 种基金Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramCAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CAS,Istituto Nazionale di Fisica Nucleare,Italy,Ministry of Development of Turkey(DPT2006K-120470)U.S.Department of Energy(DE-FG02-04ER41291,DE-FG02-91ER40682,DE-FG02-94ER40823)U.S.National Science Foundation,University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘The number of φ＇ events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×（1.00±0.81%）×10^6. The error is systematic dominant; the statistical error is negligible.
基金Supported by the Ministry of Science and Technology of China(2009CB825200)National Natural Science Foundation of China(NSFC)(11235011,11322544,11335008,11425524,11475207)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe Collaborative Innovation Center for Particlcs and Interactions(CICPI)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(11179014)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(11179007,U1232201,U1532257,U1532258)Joint Funds of the National Natural Science Foundation of China(11079008)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CASNational 1000 Talents Program of ChinaGerman Research Foundation DFG(Collaborative Research Center CRC 1044)Istituto Nazionale di Fisica Nucleare,ItalyKoninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Natural Science Foundation of China(11205082)The Swedish Research Council,U.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0010118,DE-SC-0010504)U.S.National Science Foundation,University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘The numbers of ψ（3686） events accumulated by the BESⅢ detector for the data taken during 2009 and 2012 are determined to be（107.0±0.8）×10^6 and（341.1±2.1）×10^6, respectively, by counting inclusive hadronic events,where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ（3686） events for the two data taking periods is（448.1±2.9）×10^6.
基金Supported by National Key Basic Research Program of China(2009CB825204,2015CB856700)National Natural Science Foundation of China(NSFC)(10935007,11125525,11235011,11305180,11322544,11335008,11425524,11475123)+14 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,U1532101)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CASNational 1000 Talents Program of ChinaINPAC and Shanghai Key Laboratory for Particle Physics and Cosmology,German Research Foundation DFG(Collaborative Research Center CRC-1044)Istituto Nazionale di Fisica Nucleare,Italy,Koninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Natural Science Foundation of China(NSFC)(11405046,U1332103)Russian Foundation for Basic Research(14-07-91152)Swedish Resarch Council,U.S.Department of Energy(DE-FG02-04ER41291,DE>FG02-05ER41374,DE1-SC0012069,DESC0010118)U.S.National Science Foundation,University of Groningen(RuG)Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘By analyzing 2.93 fb-1 data collected at the center-of-mass energy v/S = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D＋- k0e＋ ve via k0-π0π0 - （8.59 ± 0.14 ± 0.21）% using k0- k0-π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties..
基金Supported by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(10935007,11121092,11125525,11235011,11322544,11335008,11375170,11275189,11079030,11475164,11475169,11005109,10979095,11275211)+8 种基金Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(11179007,U1232201,U1332201,U1532102).(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,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,DEFG02-94ER40823,DESC0010118)U.S.National Science Foundation,University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung Gmb H(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘By analyzing the large-angle Bhabha scattering events e^＋e^- → （γ）e^＋e^- and diphoton events e^＋^e- → （γ）γγ for the data sets collected at center-of-mass （c.m.） energies between 2.2324 and 4.5900 GeV （131 energy points in total） with the upgraded Beijing Spectrometer （BESIII） at the Beijing Electron-Positron Collider （BEPCII）, the integrated luminosities have been measured at the different c.m. energies, individually. The results are important inputs for the R value and J/ψ resonance parameter measurements.
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)National Natural Science Foundation of China(NSFC)(11235011,11335008,11425524,11625523,11635010)+13 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFCCAS(U1332201,U1532257,U1532258)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASNational 1000 Talents Program of China,INPACShanghai 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 fundThe Swedish Research Council,U.S.Department of Energy(DEFG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069)University of Groningen(RuG)and the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘To investigate the nature of the Ψ（3770） resonance and to measure the cross section for e^＋e^-→DD, a cross-section scan data sample, distributed among 41 center-of-mass energy points from 3.73 to 3.89 GeV, was taken with the BESIII detector operated at the BEPCII collider in the year 2010. By analyzing the large angle Bhabha scattering events, we measure the integrated luminosity of the data sample at each center-of-mass energy point. The total integrated luminosity of the data sample is 76.16±0.04±0.61 pb^-1, where the first uncertainty is statistical and the second systematic.
基金Supported by the Ministry of Science and Technology of China(2009CB825204)National Natural Science Foundation of China(10625524,10821063,10825524,10835001,10935007,11125525,11235011)+7 种基金Joint Funds of the National Natural Science Foundation of China(11079008,11179007)Chinese Academy of Sciences Large-Scale Scientific Facility Program,CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CAS,German Research Foundation DFG(Collaborative Research Center CRC-1044)Istituto Nazionale di Fisica Nucleare,Italy,Ministry of Development of Turkey(DPT2006K-120470)U.S.Department of Energy(DE-FG02-04ER41291,DE-FG02-05ER41374,DE-FG02-94ER40823)U.S.National Science Foundation,University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI)Darmstadt,WCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘Data sets were collected with the BESⅢ detector at the BEPCⅡ collider at the center-of-mass energy of √s=3.650 GeV during May 2009 and at √s=3.773 GeV from January 2010 to May 2011. By analyzing the large angle Bhabha scattering events, the integrated luminosities of the two data sets are measured to be （44.49±0.02±0.44） pb-1 and （2916.94±0.18±29.17） pb-1, respectively, where the first error is statistical and the second error is systematic.
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 in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11235011,11322544,11335008,11425524,11635010,11675184,11735014)+18 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)the Collaborative Innovation Center for Particles and Interactions(CICPI)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1232201,U1332201,U1532257,U1532258)CAS(KJCX2-YW-N29,KJCX2-YW-N45)100 Talents Program of CASNational 1000 Talents Program of ChinaINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(Collaborative Research Center CRC 1044,FOR 2359)Istituto Nazionale di Fisica Nucleare,ItalyKoninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Natural Science Foundation of China(NSFC)(11505010)The Swedish Resarch CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069)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To study the nature of the state Y（2175）,a dedicated data set of e ＋ e-collision data was collected at the center-of-mass energy of 2.125 GeV with the BESⅢ detector at the BEPCⅡ collider.By analyzing large-angle Bhabha scattering events,the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb-1,where the first uncertainty is statistical and the second one is systematic.In addition,the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV,where the first uncertainty is statistical and the second one is systematic.
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 in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11235011,11275266,11335008,11425524,11625523,11635010)+16 种基金the Chinese Academy of Sciences(CAS) Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1332201,U1532257,U1532258)CAS(KJCX2-YW-N29,KJCX2-YW-N45,QYZDJ-SSW-SLH003)100 Talents Program of CASNational 1000 Talents Program of ChinaINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(Collaborative Research Center CRC 1044,FOR 2359)Istituto Nazionale di Fisica Nucleare,ItalyKoninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Science and Technology fundThe Swedish Research CouncilU.S. Department of Energy under(DE-FG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069)University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),DarmstadtWCU Program of National Research Foundation of Korea(R32-2008-000-10155-0)
文摘We study the hadronic decays of ∧c+ to the final states ∑+η and ∑+η’,using an e+e-annihilation data sample of 567 pb-1 taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCⅡ collider.We find evidence for the decays ∧c+→∑+η and ∑+η’ with statistical significance of 2.5σ and 3.2σ,respectively.Normalizing to the reference decays ∧c+→∑+π0 and ∑+ω,we obtain the ratios of the branching fractions■and ■to be 0.35±0.16±0.02 and 0.86±0.34±0.04,respectively.The upper limits at the 90% confidence level are set to be■and■.Using BESIII measurements of the branching fractions of the reference decays,we determine B（∧c+→∑+η）=（0.41±0.19±0.05）%（<0.68%）and B（∧c+→∑+η’）=（1.34±0.53 ±0.19）%（<1.9%）.Here,the first uncertainties are statistical and the second systematic.The obtained branching fraction of ∧c+→∑+η is consistent with the previous measurement,and the branching fraction of ∧c+→∑+η’ is measured for the first time.
基金Supported in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11335008,11425524,11625523,11635010,11735014)+9 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(U1532257,U1532258,U1732263)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC,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 CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0010118,DE-SC-0010504,DE-SC-0012069),University of Groningen(RuG)the Helmholtzzentrum fuer Schwerionenforschung GmbH(GSI),Darmstadt
文摘Studies of e^+e~→D_s^+■^((*)0)K^-and the P-wave charmed-strange mesons are performed based on an e^+e^-collision data sample corresponding to an integrated luminosity of 567 pb^(-1) collected with the BESIII detector at s^(1/2)=4.600 GeV. The processes of e^+e^-→D_s^+■^(*0)K^- and D_s^+■~0K^- are observed for the first time and are found to be dominated by the modes D_s^+D_(s1)(2536)^-and D_s^+D_(s2)~*(2573)^-, respectively. The Born cross sections are measured to be σ~B(e^+e^-→D_s^+■^(*0)K^-) =(10.1±2.3±0.8) pb and σ~B(e^+e^-→D_s^+■~0K^-) =(19.4±2.3± 1.6) pb, and the products of Born cross section and the decay branching fraction are measured to be σ~B(e^+e^-→D_s^+D_(s1)(2536)^-+c.c.)·B(D_(s1)(2536)^-→■^(*0)K^-)=(7.5±1.8±0.7) pb and σ~B(e^+e^-→D_s^+D_(s2)~*(2573)^-+ c.c.)·B(D_(s2)~*(2573)^-→■~0 K^-)=(19.7 ± 2.9 ±2.0) pb. For the D_(s1)(2536)^-and D_(s2)~*(2573)^-mesons, the masses and widths are measured to be M(D_(s1)(2536)^-)=(2537.7±0.5 ±3.1) MeV/c2, Γ(D_(s1)(2536)^-) =(1.7 ±1.2 ±0.6)MeV, and M(D_(s2)~*(2573)^-)=(2570.7±2.0 ±1.7) MeV/c^2, Γ(D_(s2)~*(2573)^-)=(17.2 ±3.6 ±1.1) MeV. The spin-parity of the D_(s2)~*(2573)^-meson is determined to be J^p= 2^+. In addition, the processes e^+e^-→D_s^+■^((*)0)K^-are searched for using the data samples taken at four(two) center-of-mass energies between 4.416(4.527) and 4.575 GeV, and upper limits at the 90% confidence level on the cross sections are determined.
基金Supported by Ministry of Science and Technology of China (2009CB825200)National Natural Science Foundation of China (NSFC) (10625524, 10821063, 10825524, 10835001, 10935007, 11125525)+3 种基金Joint Funds of National Natural Science Foundation of China (11079008, 11179007)Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program (KJCX2-YW-N29, KJCX2-YW-N45)100 Talents Program of CAS, Istituto Nazionale di Fisica Nucleare, Italy, U. S. Department of Energy (DE-FG02-04ER41291, DE-FG02-91ER40682, DE-FG02-94ER40823)U.S. National Science Foundation, University of Groningen (RuG) and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt, WCU Program of National Research Foundation of Korea (R32-2008-000-10155-0)
文摘The number of J/ψ events collected with the BES detector at the BEPC from June 12 to July 28, 2009 is determined to be （225.3 ± 2.8） × 10^ 6 using J/ψ→inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
基金Supported by National Natural Science Foundation of China (10475068, 10535010, 10775068, 10865004, 10905029, 11065005,11105079)973 National Major State Basic Research and Development of China (2007CB815004, 2010CB327803)China Postdoctoral Science Foundation (20100480017)
文摘We have derived a formula for the neutron radiative capture cross section in the framework of a statistical model approach to nuclear reactions. Based on this formula, new systematics are established between the （n, y） reaction cross section and the energy level density of a compound nucleus or a relative neutron excess of an even-even target nucleus for neutron incident energy above the resonance region to MeV. Good agreement with experimental data suggests that this new systematical law is helpful to nalyze the experimental data.
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.
