There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics.This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢand B facto...There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics.This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢand B factories,and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X(1835)meson state at BESⅢ,as well as the threshold measurements of charm mesons and charm baryons.We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESⅢduring the remaining operation period of BEPCⅡ.This survey will help in the optimization of the data-taking plan over the coming years,and provides physics motivation for the possible upgrade of BEPCⅡto higher luminosity.展开更多
Using a dedicated data sample taken in 2018 on the J/ψpeak,we perform a detailed study of the trigger efficiencies of the BESIII detector.The efficiencies are determined from three representative physics processes,na...Using a dedicated data sample taken in 2018 on the J/ψpeak,we perform a detailed study of the trigger efficiencies of the BESIII detector.The efficiencies are determined from three representative physics processes,namely Bhabha scattering,dimuon production and generic hadronic events with charged particles.The combined efficiency of all active triggers approaches 100%in most cases,with uncertainties small enough not to affect most physics analyses.展开更多
During the 2016-17 and 2018-19 running periods,the BESIII experiment collected 7.5 fb of e+e-collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV.These data samples are primarily used for the ...During the 2016-17 and 2018-19 running periods,the BESIII experiment collected 7.5 fb of e+e-collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV.These data samples are primarily used for the study of excited charmonium and charmoniumlike states.By analyzing the di-muon process e+e-→(γISR=FSR)μ+μ-,we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV.Through a run-by-run study,we find that the center-of-mass energies were stable throughout most of the data-collection period.展开更多
Using inclusive decays of J/ψaprecise determination of the number of J/ψevents collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψevents were recalculate...Using inclusive decays of J/ψaprecise determination of the number of J/ψevents collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψevents were recalculated to be(224.0±1.3)×106and(1088.5±4.4)×106,respectively;these numbers are in good agreement with the previous measurements.For the J/ψsample taken in 2017-2019,the number of events was determined to be(8774.0±39.4)×106.The total number of J/ψevents collected with the BESIII detector was determined to be(10087±44)×106,where the uncertainty is dominated by systematic effects,and the statistical uncertainty is negligible.展开更多
We report a search for a heavier partner of the recently observed Zcs(3985)-state,denoted as Zcs'-,in the process e+e−→K+Ds∗−D∗0+c.c.,based on e*e-collision data collected at t...We report a search for a heavier partner of the recently observed Zcs(3985)-state,denoted as Zcs'-,in the process e+e−→K+Ds∗−D∗0+c.c.,based on e*e-collision data collected at the center-of-mass energies of√s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Zcs'-is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K+recoil-mass spectra,which are probed for a potential contribution from Zcs'-→Ds∗−D∗0+c.c.We find an excess of Zcs'-→Ds*--D*0(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7sat±4.7syst.)MeV/c2.As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σBorm)and the branching fraction(B)of Zcs'-→Ds*--D*0,under different assumptions of the Zcs'-mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits ofσBorn.B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Zcs'-state and clarify its nature in the coming years.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 s1/2=4.600 GeV. The processes of e^+e^-→D_s^+■*0K^- and D_s^+■~0K^- are observed for the first time and are found to be dominated by the modes D_s^+Ds1(2536)^-and D_s^+Ds2~*(2573)^-, respectively. The Born cross sections are measured to be σ~B(e^+e^-→D_s^+■*0K^-) =(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^+Ds1(2536)^-+c.c.)·B(Ds1(2536)^-→■*0K^-)=(7.5±1.8±0.7) pb and σ~B(e^+e^-→D_s^+Ds2~*(2573)^-+ c.c.)·B(Ds2~*(2573)^-→■~0 K^-)=(19.7 ± 2.9 ±2.0) pb. For the Ds1(2536)^-and Ds2~*(2573)^-mesons, the masses and widths are measured to be M(Ds1(2536)^-)=(2537.7±0.5 ±3.1) MeV/c2, Γ(Ds1(2536)^-) =(1.7 ±1.2 ±0.6)MeV, and M(Ds2~*(2573)^-)=(2570.7±2.0 ±1.7) MeV/c^2, Γ(Ds2~*(2573)^-)=(17.2 ±3.6 ±1.1) MeV. The spin-parity of the Ds2~*(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
Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first obser...Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛc+→nπ+π0,Λc+→nπ+π-π+,and the Cabibbo-favored decayΛc+→nK-π+π+with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λc+→nπ+π0)=(0.64±0.09±0.02)%,B(Λc+→nπ+π-π+)=(0.45±0.07±0.03)%,and B(Λc+→nK-π+π+)=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛc+→nπ+π0is about one order of magnitude higher than that ofΛc+→nπ+.展开更多
We study the hadronic decays of∧c+to the final states∑+ηand∑+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 BEPCⅡcollider.We fin...We study the hadronic decays of∧c+to the final states∑+ηand∑+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 BEPCⅡcollider.We find evidence for the decays∧c+→∑+ηand∑+η’with statistical significance of 2.5σand 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+→∑+ηis consistent with the previous measurement,and the branching fraction of∧c+→∑+η’is measured for the first time.展开更多
To investigate the nature of theΨ(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...To investigate the nature of theΨ(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
Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb-1,th...Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb-1,the process e+e-→pppñπ+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 pñ and ppπ-invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.展开更多
基金Supported in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11335008,11425524,11625523,11635010,11735014,11822506,11935018)+18 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(U1532257,U1532258,U1732263)CAS Key Research Program of Frontier Science(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASCAS PIFIthe Thousand Talents Program of ChinaIN-PAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG under Contracts NosCollaborative Research Center CRC 1044,FOR 2359Istituto Nazionale di Fisica Nucleare,ItalyKoninklijke Nederlandse Akademie van Wetenschappen(KNAW)(530-4CDP03)Ministry of Development of Turkey(DPT2006K-120470)National Science and Technology fundThe Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374,DESC-0010118,DE-SC-0012069)University of Groningen(Ru G)and the Helmholtzzentrum fuer Schwerionenforschung Gmb H(GSI),Darmstadtthe Russian Ministry of Science and Higher Education(14.W03.31.0026).
摘要There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics.This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢand B factories,and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X(1835)meson state at BESⅢ,as well as the threshold measurements of charm mesons and charm baryons.We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESⅢduring the remaining operation period of BEPCⅡ.This survey will help in the optimization of the data-taking plan over the coming years,and provides physics motivation for the possible upgrade of BEPCⅡto higher luminosity.
基金Supported in part by National Key Basic Research Program of China(2015CB856700)National Natural Science Foundation of China(NSFC)(11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012)+15 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U 1732263,U 1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSWSLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)German Research Foundation DFG under Contracts Nos.Collaborative Research Center CRC 1044,FOR 2359Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development o f Turkey(DPT2006K-120470)National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DEFG02-05ER41374,DE-SC-0012069)。
摘要Using a dedicated data sample taken in 2018 on the J/ψpeak,we perform a detailed study of the trigger efficiencies of the BESIII detector.The efficiencies are determined from three representative physics processes,namely Bhabha scattering,dimuon production and generic hadronic events with charged particles.The combined efficiency of all active triggers approaches 100%in most cases,with uncertainties small enough not to affect most physics analyses.
基金Supported in part by National Key Research and Development Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012)+12 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CAS,INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology,ERC(758462)European Union Horizon 2020 research and innovation programme(Marie Sklodowska-Curie grant agreement No 894790)German Research Foundation DFG(443159800)Collaborative Research Center CRC 1044,FOR 2359,FOR 2359,GRK 214Istituto Nazionale di Fisica Nucleare,Italy,Ministry of Development of Turkey(DPT2006K-120470)National Science and Technology fund,Olle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research Council,U.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0012069)。
摘要During the 2016-17 and 2018-19 running periods,the BESIII experiment collected 7.5 fb of e+e-collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV.These data samples are primarily used for the study of excited charmonium and charmoniumlike states.By analyzing the di-muon process e+e-→(γISR=FSR)μ+μ-,we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV.Through a run-by-run study,we find that the center-of-mass energies were stable throughout most of the data-collection period.
基金Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12061131003,12075252)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union Horizon 2020 research and innovation programme Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(443159800),Collaborative Research Center CRC 1044,FOR 2359,GRK 214Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey under Contract No.DPT2006K-120470National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0012069)
摘要Using inclusive decays of J/ψaprecise determination of the number of J/ψevents collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψevents were recalculated to be(224.0±1.3)×106and(1088.5±4.4)×106,respectively;these numbers are in good agreement with the previous measurements.For the J/ψsample taken in 2017-2019,the number of events was determined to be(8774.0±39.4)×106.The total number of J/ψevents collected with the BESIII detector was determined to be(10087±44)×106,where the uncertainty is dominated by systematic effects,and the statistical uncertainty is negligible.
基金Supported in part by National Key R&D Program of China(Grant Nos.2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC)(Grant Nos.11635010,11735014,11805086,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265)+18 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(Grant No.U1832207)the CAS Center for Excellence in Particle Physics(CCEPP)100 Talents Program of CASFundamental Research Funds for the Central Universities,Lanzhou University,University of Chinese Academy of SciencesThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyERC(Grant No.758462)European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement(Grant No.894790)German Research Foundation DFG(Grant No.443159800),Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(Grant No.DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(Grant No.B16F640076)Olle Engkvist Foundation(Grant No.200-0605)STFC(United Kingdom)Suranaree University of Technology(SUT),Thailand Science Research and Innovation(TSRI),and National Science Research and Innovation Fund(NSRF)(Grant No.160355)The Royal Society,UK(Grant Nos.DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(Grant No.DE-FG02-05ER41374)。
摘要We report a search for a heavier partner of the recently observed Zcs(3985)-state,denoted as Zcs'-,in the process e+e−→K+Ds∗−D∗0+c.c.,based on e*e-collision data collected at the center-of-mass energies of√s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Zcs'-is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K+recoil-mass spectra,which are probed for a potential contribution from Zcs'-→Ds∗−D∗0+c.c.We find an excess of Zcs'-→Ds*--D*0(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7sat±4.7syst.)MeV/c2.As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σBorm)and the branching fraction(B)of Zcs'-→Ds*--D*0,under different assumptions of the Zcs'-mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits ofσBorn.B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Zcs'-state and clarify its nature in the coming years.
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
摘要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 s1/2=4.600 GeV. The processes of e^+e^-→D_s^+■*0K^- and D_s^+■~0K^- are observed for the first time and are found to be dominated by the modes D_s^+Ds1(2536)^-and D_s^+Ds2~*(2573)^-, respectively. The Born cross sections are measured to be σ~B(e^+e^-→D_s^+■*0K^-) =(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^+Ds1(2536)^-+c.c.)·B(Ds1(2536)^-→■*0K^-)=(7.5±1.8±0.7) pb and σ~B(e^+e^-→D_s^+Ds2~*(2573)^-+ c.c.)·B(Ds2~*(2573)^-→■~0 K^-)=(19.7 ± 2.9 ±2.0) pb. For the Ds1(2536)^-and Ds2~*(2573)^-mesons, the masses and widths are measured to be M(Ds1(2536)^-)=(2537.7±0.5 ±3.1) MeV/c2, Γ(Ds1(2536)^-) =(1.7 ±1.2 ±0.6)MeV, and M(Ds2~*(2573)^-)=(2570.7±2.0 ±1.7) MeV/c^2, Γ(Ds2~*(2573)^-)=(17.2 ±3.6 ±1.1) MeV. The spin-parity of the Ds2~*(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 in part by National Key R&D Program of China(2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC)(11635010,11735014,11805086,11835012,11935015,11935016,11935018,11975011,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265)+20 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)the CAS Center for Excellence in Particle Physics(CCEPP)100 Talents Program of CASFundamental Research Funds for the Central Universities,Lanzhou University,University of Chinese Academy of SciencesThe Institute of Nuclear and Particle Physics(INPAC)Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)German Research Foundation DFG(443159800)Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(B16F640076STFC)(United Kingdom)Suranaree University of Technology(SUT)Thailand Science Research and Innovation(TSRI)National Science Research and Innovation Fund(NSRF)(160355)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DEFG02-05ER41374)。
摘要Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛc+→nπ+π0,Λc+→nπ+π-π+,and the Cabibbo-favored decayΛc+→nK-π+π+with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λc+→nπ+π0)=(0.64±0.09±0.02)%,B(Λc+→nπ+π-π+)=(0.45±0.07±0.03)%,and B(Λc+→nK-π+π+)=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛc+→nπ+π0is about one order of magnitude higher than that ofΛc+→nπ+.
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)
摘要We study the hadronic decays of∧c+to the final states∑+ηand∑+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 BEPCⅡcollider.We find evidence for the decays∧c+→∑+ηand∑+η’with statistical significance of 2.5σand 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+→∑+ηis consistent with the previous measurement,and the branching fraction of∧c+→∑+η’is measured for the first time.
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)
摘要To investigate the nature of theΨ(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 in part by National Key R&D Program of China under Contracts Nos.Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(11975118,11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12061131003,12075252,12192260,12192261,12192262,12192263,12192264,12192265)+19 种基金the Natural Science Foundation of Hunan Province of China(2019JJ30019)the Science and Technology Innovation Program of Hunan Province(2020RC3054)the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union Horizon 2020 research and innovation programme under Contract No.Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(43159800)Collaborative Research Center CRC 1044,FOR 2359,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0012069)。
摘要Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb-1,the process e+e-→pppñπ+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 pñ and ppπ-invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.