Particle physics is a basic science which studies the smallest elements of matter and the properties of their interactions, deepening mankind’s knowledge of the microcosmos.τ-Charm physics is an important branch of ...Particle physics is a basic science which studies the smallest elements of matter and the properties of their interactions, deepening mankind’s knowledge of the microcosmos.τ-Charm physics is an important branch of elementary-particle physics.Systematic studies on the radiative decay,strong decay and weak decay of elementary particles will resolve and clarify many problems in the discipline, testing and deveploping the Standard Model of elementary particles.For example,what is the展开更多
The Institute of High Energy Physics of Chinese Academy of Sciences organized a workshop to estab- lish closer contacts between experimentalists （theorists） involved in the studies of charm physics from both c and B...The Institute of High Energy Physics of Chinese Academy of Sciences organized a workshop to estab- lish closer contacts between experimentalists （theorists） involved in the studies of charm physics from both c and B communities. The workshop covers talks of physics analysis and its results from four electron-positron colliding experiments （BES, Belle, CLEO and BaBar）. Presentations at the workshop are organized in the following sessions ： （1） Hadron spectroscopy and new resonances; （2） D^0-D^0 mixing; （3） Charmonium decays; （4） Charm hadronic and （semi-）leptonic decays; （5） QCD at low energy and T physics; （6） Partial wave analysis and Dalitz analysis, MC generator and Tools; （7） Detector upgrade. The workshop was held during November 26 27, 2007 in the Institute of High Energy Physics （IHEP）. There are 90 registered participants in total, and 38 of them are from abroad （Japan, America, Russia, Italy, Germany, France, Slovenia, Switzerland and so on） and the others from China. All 35 talks were given in a plenary session.展开更多
The charmed baryon was first observed experimentally in 1975,one year after the charm quark's confirmation via the discovery of the J/ψ particle.Studying charmed baryon decays provides a pathway to investigate bo...The charmed baryon was first observed experimentally in 1975,one year after the charm quark's confirmation via the discovery of the J/ψ particle.Studying charmed baryon decays provides a pathway to investigate both strong and weak interactions,leveraging the weak decays of the embedded charm quark.However,for approximately three decades following its discovery,experimental knowledge of charmed baryons remained significantly limited compared to those of the hidden-charm ψ mesons and open-charm D_((s))mesons.This situation changed markedly starting in 2014,when dedicated data collection for charmed baryons commenced at BESIII.In this article,we review the experimental progress achieved since 2014 in understanding the weak decays of the charmed baryons.展开更多
An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions re...An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of Vs=7,8,and 13Tev,corresponding to a total integrated luminosity of 9fb-1.A clear double-peak structure is observed in the m(π+π~)spectrum of the Ds1(2460)+→D,π+π-decay.The data can be described either with a model including fo(500),o(980),and f2(1270)resonances,in which the contributions of fo(980)and f2(1270)are unexpectedly large,or with a model including fo(500),a doubly charged open-charm tetraquark state Tt and its isospin partner Tes.If the former is considered implausible,the Tes states are observed with high significance,and the data are consistent with isospin symmetry.When imposing isospin constraints between the two Tes states,their mass and width are determined to be(2327±13±13)Mev and(96±16+70)Mev,respectively,where the first uncertainty is statistical 23 and the second is systematic.The mass is slightly below the DK threshold,and a spin-parity of o+is favoured with high significance.展开更多
We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant si...We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant signal is not observed,and an upper limit on the branching fraction of D^(+)→e^(+)ν_(e)is set as 9.7×10^(-7),at a confidence level of 90%.Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.展开更多
A measurement of the lifetimes of theΩ_(c)^(0)andΞ_(c)^(0)baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.4 fb;collected by ...A measurement of the lifetimes of theΩ_(c)^(0)andΞ_(c)^(0)baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.4 fb;collected by the LHCb experiment.TheΩ_(c)^(0)andΞ_(c)^(0)baryons are produced directly from proton interactions and reconstructed in the p K^(-)K^(+)π^(+)nal state.TheΩ_(c)^(0)lifetime is measured to be 276.5±13.4±4.4±0.7 fs,and theΞ_(c)^(0)lifetime is measured to be 148.0±2.3±2.2±0.2 fs,where the first uncertainty is statistical,the second systematic,and the third due to the uncertainty on the D^(0)lifetime.These results con firm previous LHCb measurements based on semileptonic beauty-hadron decays,which disagree with earlier results of a four times shorterΩ_(c)^(0)lifetime,and provide the single most precise measurement of theΩ_(c)^(0)lifetime.展开更多
A first search for the Ξ_(bc)^(+)J/ψΞ_(c)^(+) decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass...A first search for the Ξ_(bc)^(+)J/ψΞ_(c)^(+) decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass energies of 7, 8, and 13 TeV. Two peaking structures are seen with a local (global) significance of 4.3(2.8) and 4.1(2.4) standard deviations at masses of 6571 and 6694 MeV/c2, respectively. Upper limits are set on the Ξ+bc baryon production cross-section times the branching fraction relative to that of the B+c→J/ψD+s decay at centre-of-mass energies of 8 and 13 TeV, in the Ξ+bc and in the B+c rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to 20GeV/c, respectively. Upper limits are presented as a function of the Ξ+bc mass and lifetime.展开更多
Recent experimental results from Beijing Spectroscopy(BES)are reviewed,including the hadron spectroscopy from J/ψdecays,and a number of new states are found or confirmed,includingσ,κ,X(1835),ωφthreshold enhanceme...Recent experimental results from Beijing Spectroscopy(BES)are reviewed,including the hadron spectroscopy from J/ψdecays,and a number of new states are found or confirmed,includingσ,κ,X(1835),ωφthreshold enhancement in J/ψ→γωφ,a broad resonance in J/ψ→K+K?π0,decay studies ofψ(2S)andχCJ,as well as the results ofψ(3770)non-D$\bar D$decays.The current status of BEPCII/BESIII,the major upgrade of BEPC/BESII,is also reported.展开更多
文摘Particle physics is a basic science which studies the smallest elements of matter and the properties of their interactions, deepening mankind’s knowledge of the microcosmos.τ-Charm physics is an important branch of elementary-particle physics.Systematic studies on the radiative decay,strong decay and weak decay of elementary particles will resolve and clarify many problems in the discipline, testing and deveploping the Standard Model of elementary particles.For example,what is the
文摘The Institute of High Energy Physics of Chinese Academy of Sciences organized a workshop to estab- lish closer contacts between experimentalists （theorists） involved in the studies of charm physics from both c and B communities. The workshop covers talks of physics analysis and its results from four electron-positron colliding experiments （BES, Belle, CLEO and BaBar）. Presentations at the workshop are organized in the following sessions ： （1） Hadron spectroscopy and new resonances; （2） D^0-D^0 mixing; （3） Charmonium decays; （4） Charm hadronic and （semi-）leptonic decays; （5） QCD at low energy and T physics; （6） Partial wave analysis and Dalitz analysis, MC generator and Tools; （7） Detector upgrade. The workshop was held during November 26 27, 2007 in the Institute of High Energy Physics （IHEP）. There are 90 registered participants in total, and 38 of them are from abroad （Japan, America, Russia, Italy, Germany, France, Slovenia, Switzerland and so on） and the others from China. All 35 talks were given in a plenary session.
基金supported in part by National Natural Science Foundation of China(12221005,12422504)CAS Project for Young Scientists in Basic Research(YSBR-117)Fundamental Research Funds for the Central Universities,Lanzhou University(lzujbky-2025-ytB01,lzujbky-2023-stlt01,lzujbky-2023-it32),University of Chinese Academy of Sciences。
文摘The charmed baryon was first observed experimentally in 1975,one year after the charm quark's confirmation via the discovery of the J/ψ particle.Studying charmed baryon decays provides a pathway to investigate both strong and weak interactions,leveraging the weak decays of the embedded charm quark.However,for approximately three decades following its discovery,experimental knowledge of charmed baryons remained significantly limited compared to those of the hidden-charm ψ mesons and open-charm D_((s))mesons.This situation changed markedly starting in 2014,when dedicated data collection for charmed baryons commenced at BESIII.In this article,we review the experimental progress achieved since 2014 in understanding the weak decays of the charmed baryons.
基金support from CERN and from the national agencies:CAPES,CNPq,FAPERJ and FINEP(Brazil)MOST and NSFC(China)+12 种基金CNRS/IN2P3(France)BMBF,DFG and MPG(Germany)INFN(Italy)NWO(Netherlands)MNi SW and NCN(Poland)MCID/IFA(Romania)MICIU and AEI(Spain)SNSF and SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NP and NSF(USA)Key Research Program of Frontier Sciences of CAS,CAS PIFI,CAS CCEPP,Fundamental Research Funds for the Central UniversitiesSci.&Tech.Program of Guangzhou(China)。
文摘An amplitude analysis of the Dsi(2460)+→D,π+π-transition is performed simultaneously in BO→D'D,π+π-,B+-D'D,π+π,and BO-D-D,π+π-decays.The study is based on a data sample of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of Vs=7,8,and 13Tev,corresponding to a total integrated luminosity of 9fb-1.A clear double-peak structure is observed in the m(π+π~)spectrum of the Ds1(2460)+→D,π+π-decay.The data can be described either with a model including fo(500),o(980),and f2(1270)resonances,in which the contributions of fo(980)and f2(1270)are unexpectedly large,or with a model including fo(500),a doubly charged open-charm tetraquark state Tt and its isospin partner Tes.If the former is considered implausible,the Tes states are observed with high significance,and the data are consistent with isospin symmetry.When imposing isospin constraints between the two Tes states,their mass and width are determined to be(2327±13±13)Mev and(96±16+70)Mev,respectively,where the first uncertainty is statistical 23 and the second is systematic.The mass is slightly below the DK threshold,and a spin-parity of o+is favoured with high significance.
基金Supported in part by the National Key R&D Program of China(2023YFA1606000,2020YFA0406400,2020YFA0406300)the National Natural Science Foundation of China(NSFC)(11635010,11735014,11935015,11935016,11875054,11935018,12025502,12035009,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+12 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U2032104,U1832207)the 100 Talents Program of CAS,the Excellent Youth Foundation of Henan Scientific Commitee(242300421044)the Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and Cosmology,the German Research Foundation DFG(FOR5327)the Istituto Nazionale di Fisica Nucleare,Italy,the Knut and Alice Wallenberg Foundation(2021.0174,2021.0299)the Ministry of Development of Turkey(DPT2006K-120470),the National Research Foundation of Korea(NRF-2022R1A2C1092335)the National Science and Technology Fund of Mongoliathe National Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research,and Innovation of Thailand(B16F640076,B50G670107)the Polish National Science Center(2019/35/O/ST2/02907)the Swedish Research Council(2019.04595)the Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)the US Department of Energy(DE-FG02-05ER41374)。
文摘We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant signal is not observed,and an upper limit on the branching fraction of D^(+)→e^(+)ν_(e)is set as 9.7×10^(-7),at a confidence level of 90%.Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.
文摘A measurement of the lifetimes of theΩ_(c)^(0)andΞ_(c)^(0)baryons is reported using proton-proton collision data at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.4 fb;collected by the LHCb experiment.TheΩ_(c)^(0)andΞ_(c)^(0)baryons are produced directly from proton interactions and reconstructed in the p K^(-)K^(+)π^(+)nal state.TheΩ_(c)^(0)lifetime is measured to be 276.5±13.4±4.4±0.7 fs,and theΞ_(c)^(0)lifetime is measured to be 148.0±2.3±2.2±0.2 fs,where the first uncertainty is statistical,the second systematic,and the third due to the uncertainty on the D^(0)lifetime.These results con firm previous LHCb measurements based on semileptonic beauty-hadron decays,which disagree with earlier results of a four times shorterΩ_(c)^(0)lifetime,and provide the single most precise measurement of theΩ_(c)^(0)lifetime.
基金The project support from CERN and from the national agencies:CAPES,CNPq,FAPERJ and FINEP(Brazil)MOST and NSFC(China)+18 种基金CNRS/IN2P3(France)BMBF,DFG and MPG(Germany)INFN(Italy)NWO(Netherlands)MNiSW and NCN(Poland)MEN/IFA(Romania)MICINN(Spain)SNSF and SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)DOE NP and NSF(USA).We acknowledge the computing resources that are provided by CERN,IN2P3(France),KIT and DESY(Germany),INFN(Italy),SURF(Netherlands),PIC(Spain),GridPP(United Kingdom),CSCS(Switzerland),IFIN-HH(Romania),CBPF(Brazil),Polish WLCG(Poland)and NERSC(USA).Individual groups or members have received support from ARC and ARDC(Australia)Minciencias(Colombia)AvH Foundation(Germany)EPLANET,Marie Sklodowska-Curie Actions and ERC(European Union)A*MIDEX,ANR,IPhU and Labex P2IO,and Région Auvergne-RhôneAlpes(France)Key Research Program of Frontier Sciences of CAS,CAS PIFI,CAS CCEPP,Fundamental Research Funds for the Central Universities,and Sci.&Tech.Program of Guangzhou(China)GVA,XuntaGal,GENCAT and Prog.Atracción Talento,CM(Spain)SRC(Sweden)the Leverhulme Trust,the Royal Society and UKRI(United Kingdom).
文摘A first search for the Ξ_(bc)^(+)J/ψΞ_(c)^(+) decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of 9 fb−1 recorded at centre-of-mass energies of 7, 8, and 13 TeV. Two peaking structures are seen with a local (global) significance of 4.3(2.8) and 4.1(2.4) standard deviations at masses of 6571 and 6694 MeV/c2, respectively. Upper limits are set on the Ξ+bc baryon production cross-section times the branching fraction relative to that of the B+c→J/ψD+s decay at centre-of-mass energies of 8 and 13 TeV, in the Ξ+bc and in the B+c rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to 20GeV/c, respectively. Upper limits are presented as a function of the Ξ+bc mass and lifetime.
基金Supported by the National Natural Science Foundation of China(Grant No.10491300)
文摘Recent experimental results from Beijing Spectroscopy(BES)are reviewed,including the hadron spectroscopy from J/ψdecays,and a number of new states are found or confirmed,includingσ,κ,X(1835),ωφthreshold enhancement in J/ψ→γωφ,a broad resonance in J/ψ→K+K?π0,decay studies ofψ(2S)andχCJ,as well as the results ofψ(3770)non-D$\bar D$decays.The current status of BEPCII/BESIII,the major upgrade of BEPC/BESII,is also reported.
