Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order...Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order QCD diagrams would give the dominant contributions to these processes,and the corresponding branching fractions,for instance,B(Z→J/ΨJ/Ψ),have been estimated to be approximately 10^(-13)in literature.However,these decays could also happen through electromagnetic transitions Z→Vγ^(*)and Z→Pγ^(*),with the virtual photon transforming into V.Interestingly,the smallness of the vector quarkonium mass can give rise to a large factor m_(Z)^(2)/m_(V)^(2)relative to the QCD contributions,which thus counteracts the suppression from the electromagnetic coupling.We systematically include these two types of contributions in our calculation to predict branching fractions for these decays.Particularly,owing to the virtual photon effects,it is found that B(Z→J/ΨJ/Ψ)will be significantly enhanced,up to 10^(-10).展开更多
The electromagnetic radiative transition widths for heavy quarkonia, as well as digamma and digluon decay widths, are computed in the framework of the extended harmonic confinement model （ERHM） and Coulomb plus powe...The electromagnetic radiative transition widths for heavy quarkonia, as well as digamma and digluon decay widths, are computed in the framework of the extended harmonic confinement model （ERHM） and Coulomb plus power potential （CPP,） with varying potential index v. The outcome is compared with the values obtained from other theoretical models and experimental results. While the mass spectra, digamma and digluon widths from ERHM as well as CPP v=1 are in good agreement with experimental data, the electromagnetic transition widths span over a wide range for the potential models considered here making it difficult to prefer a particular model over the others because of the lack of experimental data for most transition widths.展开更多
Based on a systematic investigation of J/ψ（ψ＇）→VP, where V and P stand for light vector and pseudoscalar mesons, we identify the role played by the electromagnetic （EM） transitions and intermediate meson loop ...Based on a systematic investigation of J/ψ（ψ＇）→VP, where V and P stand for light vector and pseudoscalar mesons, we identify the role played by the electromagnetic （EM） transitions and intermediate meson loop transitions, which are essential ingredients for understanding the J/ψ and ψ＇ couplings to VP. We show that on the one hand, the EM transitions have relatively larger interferences in ψ＇→ρπ and K^＊^-K ＋c.c. as explicitly shown by vector meson dominance （VMD）. On the other hand, the strong decay of ψ＇ receives relatively larger destructive interferences from the intermediate meson loop transitions. By identifying these mechanisms in an overall study of J/ψ（ψ＇） → VP, we provide a coherent understanding of the so-called ＂ρπ puzzle＂.展开更多
In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic SchrSdinger equation by employing an approximate inter quark-antiquark potential. The spin hyperf...In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic SchrSdinger equation by employing an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are employed to compute the spectroscopy of the excited S states and a few low-lying P and D waves. The resultant wave functions at zero inter- quark separation as well as some finite separations are employed to predict the di-gamma, di-leptonic and di-gluon decay rates of charmonia states using the conventional Van Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also computed by incorporating the relativistic corrections of order v4 within the NRQCD formalism. We have observed that the NRQCD predictions with their matrix elements computed at finite radial separation yield results which are found to be in better agreement with experimentM values for both di-gamma and di-leptonic decays. The same scenario is seen in the case when di-gamma and di-leptonic decay widths are computed with the Van Royen- Weisskopf formula. It is also observed that the di-gluon decay width with the inclusion of binding energy effects are in better agreement with the experimental data available for 1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are Mso predicted. Thus, the present study of decay rates clearly indicates the importance of binding energy effects.展开更多
We investigate instanton effects on the heavy-quark potential, including its spin-dependent part, based on the instanton liquid model. Starting with the central potential derived from the instanton vacuum, we obtain t...We investigate instanton effects on the heavy-quark potential, including its spin-dependent part, based on the instanton liquid model. Starting with the central potential derived from the instanton vacuum, we obtain the spin-dependent part of the heavy-quark potential. We discuss the results of the heavy-quark potential from the instanton vacuum. Finally, we solve the nonrelativistic two-body problem, associated with the heavy-quark potential from the instanton vacuum. The instanton effects on the quarkonia spectra are marginal but are required for quantitative description of the spectra.展开更多
We discuss the shape of threshold signals in production cross sections of the reaction e＋e- → D＊ Dˉ＊, at the opening of the Ds＊ Dˉs＊ and Λc＋ Λ＋c channels. Furthermore, evidence for the ψ（3D）, ψ（5S）,...We discuss the shape of threshold signals in production cross sections of the reaction e＋e- → D＊ Dˉ＊, at the opening of the Ds＊ Dˉs＊ and Λc＋ Λ＋c channels. Furthermore, evidence for the ψ（3D）, ψ（5S）, ψ（4D）, ψ（6S）, ψ（5D）, ψ（7S）, ψ（6D）, and ψ（8S） new charmonium vector resonances is presented, on the basis of data recently published by the BABAR Collaboration. Central masses and resonance widths are estimated. Confirmation of these resonances would be a huge step in lifting the precision level of hadron spectroscopy towards that of atomic spectroscopy, with far-reaching consequences for theory.展开更多
Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e＋e-→γχc,j （J =0, 1, 2...Using data samples collected at center-of-mass energies of √s=4.009, 4.230, 4.260, and 4.360 GeV with the BES0 detector operating at the BEPC/ collider, we perform a search for the process e＋e-→γχc,j （J =0, 1, 2） and find evidence for e＋e-→γχc1 and e＋e-→γχc2 with statistical significances of 3.0σ and 3.4σ, respectively. The Born cross sections σB（e＋e-→γχc,j）, as well as their upper limits at the 90% con dence level （C.L.） are determined at each center-of-mass energy.展开更多
基金Supported in part by the National Natural Science Foundation of China(11575175,12047502)National Research and development Program of China(2020YFA0406400)。
文摘Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order QCD diagrams would give the dominant contributions to these processes,and the corresponding branching fractions,for instance,B(Z→J/ΨJ/Ψ),have been estimated to be approximately 10^(-13)in literature.However,these decays could also happen through electromagnetic transitions Z→Vγ^(*)and Z→Pγ^(*),with the virtual photon transforming into V.Interestingly,the smallness of the vector quarkonium mass can give rise to a large factor m_(Z)^(2)/m_(V)^(2)relative to the QCD contributions,which thus counteracts the suppression from the electromagnetic coupling.We systematically include these two types of contributions in our calculation to predict branching fractions for these decays.Particularly,owing to the virtual photon effects,it is found that B(Z→J/ΨJ/Ψ)will be significantly enhanced,up to 10^(-10).
基金Supported by University Grants Commission,India for Major Research Project F.No.42-775/2013(SR)(J N Pandya)Dept.of Science and Technology,India,under SERC fast track scheme SR/FTP/PS-152/2012(A K Rai)
文摘The electromagnetic radiative transition widths for heavy quarkonia, as well as digamma and digluon decay widths, are computed in the framework of the extended harmonic confinement model （ERHM） and Coulomb plus power potential （CPP,） with varying potential index v. The outcome is compared with the values obtained from other theoretical models and experimental results. While the mass spectra, digamma and digluon widths from ERHM as well as CPP v=1 are in good agreement with experimental data, the electromagnetic transition widths span over a wide range for the potential models considered here making it difficult to prefer a particular model over the others because of the lack of experimental data for most transition widths.
基金Supported by National Natural Science Foundation of China (10675131,10491306,10547001,90403031)Chinese Academy of Sciences (KJCX3-SYW-N2)UK EPSRC(GR/S99433/01)
文摘Based on a systematic investigation of J/ψ（ψ＇）→VP, where V and P stand for light vector and pseudoscalar mesons, we identify the role played by the electromagnetic （EM） transitions and intermediate meson loop transitions, which are essential ingredients for understanding the J/ψ and ψ＇ couplings to VP. We show that on the one hand, the EM transitions have relatively larger interferences in ψ＇→ρπ and K^＊^-K ＋c.c. as explicitly shown by vector meson dominance （VMD）. On the other hand, the strong decay of ψ＇ receives relatively larger destructive interferences from the intermediate meson loop transitions. By identifying these mechanisms in an overall study of J/ψ（ψ＇） → VP, we provide a coherent understanding of the so-called ＂ρπ puzzle＂.
基金Supported by Major Research Project NO.F.40-457/2011(SR),UGC,India
文摘In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic SchrSdinger equation by employing an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are employed to compute the spectroscopy of the excited S states and a few low-lying P and D waves. The resultant wave functions at zero inter- quark separation as well as some finite separations are employed to predict the di-gamma, di-leptonic and di-gluon decay rates of charmonia states using the conventional Van Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also computed by incorporating the relativistic corrections of order v4 within the NRQCD formalism. We have observed that the NRQCD predictions with their matrix elements computed at finite radial separation yield results which are found to be in better agreement with experimentM values for both di-gamma and di-leptonic decays. The same scenario is seen in the case when di-gamma and di-leptonic decay widths are computed with the Van Royen- Weisskopf formula. It is also observed that the di-gluon decay width with the inclusion of binding energy effects are in better agreement with the experimental data available for 1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are Mso predicted. Thus, the present study of decay rates clearly indicates the importance of binding energy effects.
基金Supported by Basic Science Research Program through the National Research Foundation(NRF)of Korea funded by the Korean government(Ministry of Education,Science and Technology,MEST)Grant Numbers 2016R1D1A1B03935053(UY)and 2015R1D1A1A01060707(HChK)partly Supported by RIKEN iTHES Project
文摘We investigate instanton effects on the heavy-quark potential, including its spin-dependent part, based on the instanton liquid model. Starting with the central potential derived from the instanton vacuum, we obtain the spin-dependent part of the heavy-quark potential. We discuss the results of the heavy-quark potential from the instanton vacuum. Finally, we solve the nonrelativistic two-body problem, associated with the heavy-quark potential from the instanton vacuum. The instanton effects on the quarkonia spectra are marginal but are required for quantitative description of the spectra.
文摘We discuss the shape of threshold signals in production cross sections of the reaction e＋e- → D＊ Dˉ＊, at the opening of the Ds＊ Dˉs＊ and Λc＋ Λ＋c channels. Furthermore, evidence for the ψ（3D）, ψ（5S）, ψ（4D）, ψ（6S）, ψ（5D）, ψ（7S）, ψ（6D）, and ψ（8S） new charmonium vector resonances is presented, on the basis of data recently published by the BABAR Collaboration. Central masses and resonance widths are estimated. Confirmation of these resonances would be a huge step in lifting the precision level of hadron spectroscopy towards that of atomic spectroscopy, with far-reaching consequences for theory.
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.
