The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study ...The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study the electromagnetic properties of the excitation of the negative parity the N~*(1535) resonances in the nonrelativistic constituent quark model at large momentum transfers and have performed a calculation the longitudinal and transverse helicity amplitudes. Since the helicity amplitudes depend strongly on the quark wave function in this paper, we consider the baryon as a simple, non-relativistically three-body quark model and also consider a hypercentral potential scheme for the internal baryon structure, which makes three-body forces among three quarks. Since the hyper central potential depends only on the hyper radius, therefore, the Cornell potential which is a combination of the Coulombic-like term plus a linear confining term is considered as the potential for interaction between quarks. In our work, in solving the Schrodinger equation with the Cornell potential, the Nikiforov–Uvarov method employed, and the analytic eigen-energies and eigen-functions obtained. By using the obtained eigen-functions, the transition amplitudes calculated. We show that our results in the range Q^2> 2GeV^2 lead to an overall better agreement with the experimental data in comparison with the other three non-relativistic quark models.展开更多
The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the mod...The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the modified equations of motion. Next, using novel transformations, we solve the equation of motion and report the exact analytical solutions.展开更多
We present several numerical methods and establish their error estimates for the discretization of the nonlinear Dirac equation （NLDE） in the nonrelativistic limit regime, involving a small dimensionless parameter 0...We present several numerical methods and establish their error estimates for the discretization of the nonlinear Dirac equation （NLDE） in the nonrelativistic limit regime, involving a small dimensionless parameter 0 〈 ε〈〈1 which is inversely proportional to the speed of light. In this limit regime, the solution is highly oscillatory in time, i.e., there are propagating waves with wavelength O（ ε^2） and O（1） in time and space, respectively. We begin with the conservative Crank-Nicolson finite difference （CNFD） method and establish rigorously its error estimate which depends explicitly on the mesh size h and time step τ- as well as the small parameter 0 〈 ε≤1 Based on the error bound, in order to obtain ＇correct＇ numerical solutions in the nonrelativistic limit regime, i.e., 0 〈 ε≤1 , the CNFD method requests the ε-scalability： τ- = O（ε3） and h = O（√ε）. Then we propose and analyze two numerical methods for the discretization of NLDE by using the Fourier spectral discretization for spatial derivatives combined with the exponential wave integrator and time- splitting technique for temporal derivatives, respectively. Rigorous error bounds for the two numerical methods show that their ε-scalability is improved to τ = O（ε2） and h = O（1） when 0 〈 ε 〈〈 1. Extensive numerical results are reported to confirm our error estimates.展开更多
A thorough study reveals that the only key parameter forψ(J/ψ,ψ')polarization at hadron colliders is the ratio〈Oψ(3S1[8])〉/〈Oψ(3P0[8])〉angle,if the velocity scaling rule holds.A slight variation of this p...A thorough study reveals that the only key parameter forψ(J/ψ,ψ')polarization at hadron colliders is the ratio〈Oψ(3S1[8])〉/〈Oψ(3P0[8])〉angle,if the velocity scaling rule holds.A slight variation of this parameter results in substantial change of theψpolarization.We find that with equally good description of the yield data,this parameter can vary significantly.Fitting the yield data is therefore incapable of determining this parameter,and consequently,of determining theψpolarization.We provide a universal approach to fixing the long-distance matrix elements(LDMEs)for J/ψandψ'production.Further,with the existing data,we implement this approach,obtain a favorable set of the LDMEs,and manage to reconcile the charmonia production and polarization experiments,except for two sets of CDF data on J/ψpolarization.展开更多
Using the scale evolution of nuclear parton distributions,the contribution of color-octet heavy quarkonium production mechanism to the P + Fe → J/ψ + γ + X process in calculated and discussed.Comparing our theoreti...Using the scale evolution of nuclear parton distributions,the contribution of color-octet heavy quarkonium production mechanism to the P + Fe → J/ψ + γ + X process in calculated and discussed.Comparing our theoretical results with the future experimental data,the color-octet heavy quarkonium production mechanism can be examined.展开更多
The neutrinos of the early universe evolved from a relativistic phase at very early times to a massive particle behavior at later times.First,the kinetic energy of neutrinos is relativistic,and as a result,neutrinos c...The neutrinos of the early universe evolved from a relativistic phase at very early times to a massive particle behavior at later times.First,the kinetic energy of neutrinos is relativistic,and as a result,neutrinos can be described as massless particles.As the Universe expands,the temperature drops and the kinetic energy decreases,and the neutrinos turn into a non-relativistic phase with a non-negligible mass.In this paper,we first put constraints on the total mass of neutrinos.Then we investigate the effect of neutrinos on the CMB power spectrum,P(k),in the case of massless and massive neutrinos using the publicly available Boltzmann code CAMB and we prove that when neutrino coupled to scalar field the CMB power spectrum has a little shift,which means that the power spectrum of CMB is greatly affected by the background energy density and the accelerated expansion of the Universe.Furthermore,we investigate the effect of perturbed quintessence on this spectrum and find that the highest peaks of this spectrum are shifted to smaller scales.Also,we estimate the Deceleration-Acceleration(DA)redshift transition(z_(da))using the coupling canonical scalar field with neutrinos.For Pantheon data we obtain z_(da)=0.7±0.05 and for CC data z_(da)=0.68±0.03.In the presence of neutrinos the DA redshift transition is z_(da)=0.42±0.03 for Pantheon data and z_(da)=0.49±0.05 for CC data.These results indicate that neutrinos can affect this phase transition.The results obtained in this article show that when the mass of neutrinos increases,the value of the background energy density increases,resulting in a higher power spectrum peak.Also,by examining the effect of coupling neutrinos to dark energy,we find that the transition occurs at lower redshift.展开更多
In this paper, a quantum mechanical Green’s function for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator (qo)...In this paper, a quantum mechanical Green’s function for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator (qo) to the harmonic oscillator (ho);second [2], the integration of the classical action function for the quartic oscillator. Here an equivalent form for the quartic oscillator action function in terms of harmonic oscillator variables is derived in order to facilitate the derivation of the quartic oscillator Green’s Function, namely in fixing its amplitude.展开更多
A method of Foldy-Wouthuysen transformation for relativistic spin-1/2 particles in external fields is proposed;in the present work the basic properties of the Dirac hamiltonian in the FW representation in the noncommu...A method of Foldy-Wouthuysen transformation for relativistic spin-1/2 particles in external fields is proposed;in the present work the basic properties of the Dirac hamiltonian in the FW representation in the noncommutative phase-space are investigated and the Schrödinger-Pauli equation is found, knowing that the used methods for extracting the full phase-space noncommutative Dirac equation are, the Bopp-shift linear translation method, and the Moyal-Weyl product (*-product).展开更多
We use a non-relativistic model to study the spectroscopy of a tetraquark composed of [cc]■ in a diquark-antidiquark configuration.By numerically solving the Schr?dinger equation with a Cornell-inspired potential,we ...We use a non-relativistic model to study the spectroscopy of a tetraquark composed of [cc]■ in a diquark-antidiquark configuration.By numerically solving the Schr?dinger equation with a Cornell-inspired potential,we separate the four-body problem into three two-body problems.Spin-dependent terms(spin-spin,spin-orbit and tensor)are used to describe the splitting structure of the ■ spectrum and are also extended to the interaction between diquarks.Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained.We find that the spin-dependent interaction is sizable in the diquark-antidiquark system,despite the heavy diquark mass,and also that the diquark has a finite size if treated in the same way as the ■ systems.We find that the lowest S-wave T 4c tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs,while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds.Finally,we repeat the calculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks.This might be relevant to the study of exotic charmonium in the quark-gluon plasma.The T 4c states could be investigated in the forthcoming experiments at the LHC and BelleⅡ.展开更多
We have studied Z+(4430)as a D*D1 molecule from the quark model,state mixing effect is considered by solving the coupled channel Schrdinger equation numerically. More precise measurements of Z+(4430)mass and width,par...We have studied Z+(4430)as a D*D1 molecule from the quark model,state mixing effect is considered by solving the coupled channel Schrdinger equation numerically. More precise measurements of Z+(4430)mass and width,partial wave analysis are helpful to understand its structure. If it lies below the D*D1 threshold,molecule interpretation with JP=1-is favored,and JP=0-can not be ruled out. Otherwise Z+(4430)may be a virtual state with JP=2-. The analogous heavy flavor mesons Z+bb and Z++bc are considered as well,and the masses predicted in our model are in agreement with the predictions from the potential model and QCD sum rule.展开更多
We demonstrate that the recently proposed soft gluon factorization(SGF)is equivalent to the nonrelativistic QCD(NRQCD)factorization for heavy quarkonium production or decay,which means that,for any given process,these...We demonstrate that the recently proposed soft gluon factorization(SGF)is equivalent to the nonrelativistic QCD(NRQCD)factorization for heavy quarkonium production or decay,which means that,for any given process,these two factorization theories are either both valid or both violated.We use two methods to arrive at this conclusion.In the first method,we apply the two factorization theories to the physical process J/ψ→e^+e^-.Our explicit calculation shows that both SGF and NRQCD can correctly reproduce the low energy physics of full QCD,and the two factorizations are thus equivalent.In the second method,by using equations of motion,we successfully deduce SGF from NRQCD effective field theory.By identifying SGF with NRQCD factorization,we establish relations between the two factorization theories and prove the generalized Gremm-Kapustin relation as a byproduct.Compared with the NRQCD factorization,the advantage of SGF is that it resums the series of relativistic corrections originating from kinematic effects to all powers,yielding better convergence of the relativistic expansion.展开更多
We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interfer...We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interferences between the Zb-exchange and the bottom meson loops mechanisms,we predict two possible branching ratios for each process:BRγ(4 S)→hb(1 P)π+π-≈(1.20.40.8×10^-6)or(0.5-0.20.5×10^-6),and BRγ(4 S)→(2 P)π+π-≈(7.1-1.1+1.7×10^-10)or(2.4-0.10.2×10^-10)).The contribution of the bottom meson loops is found to be considerably larger than that of the Zbexchange in the T(4 S)→hb(1 P)ππtransitions,while its decay rates are not comparable to those of heavy quark spin conservedγ(4 S)→γ(1 S,2 S)ππprocesses.We also predict the contribution of the charm meson loops in the branch fractions ofΨ(3 S,4 S)→hc(1 P)ππ.展开更多
Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect p...Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect production of theΞbc andΞbb baryons via the Z-boson decay process Z→Ξbo+b+Q with a Q=(c,b)quark under the NRQCD factorization approach.After considering the contibution from the diquark states(be)PSil3/6,<bc)[^(1)Sol3/6,(bb)[^(3)Sol6,and(bb)[3S1l3,the calculated branching fractions are B(Z-→Ξbe+X)=3.595×10^(-5)and B(Z→Ξbb+X)=1.213×10^(-6).Furthermore,theΞbe andΞbb production events are predicted to be of the order of 104 and 103 at the LHC collider,and the order of 107 and 106 for the CEPC collider.We then estimate the produc tion ratio for Z→c2(bb)→Ξbc+X withΞbc→Λ^(+)_(c)in Z-boson decay,that is,R(Z→cc→Ξ0bc+X)~0(10^(-6))br and R(Z→bb→Ξbc+X)~0(10^(-5)),respectively.Finally,we present the differential decay widths ofΞbc andΞbb with respect to 823 and z distributions and analyze the uncertainties.展开更多
The decay constants of the low lying S-wave B_(c)mesons,i.e.B_(c)(nS) and B_(c)^(*)(nS) with n ≤3,are calculated in the nonrelativistic quark model.The running coupling of the strong interaction is taken into account...The decay constants of the low lying S-wave B_(c)mesons,i.e.B_(c)(nS) and B_(c)^(*)(nS) with n ≤3,are calculated in the nonrelativistic quark model.The running coupling of the strong interaction is taken into account,and the uncertainties due to varying parameters and losing Lorentz covariance are considered carefully.As a byproduct,the decay constants of the low lying S-wave charmonium and bottomium states are given in the appendixes.展开更多
文摘The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study the electromagnetic properties of the excitation of the negative parity the N~*(1535) resonances in the nonrelativistic constituent quark model at large momentum transfers and have performed a calculation the longitudinal and transverse helicity amplitudes. Since the helicity amplitudes depend strongly on the quark wave function in this paper, we consider the baryon as a simple, non-relativistically three-body quark model and also consider a hypercentral potential scheme for the internal baryon structure, which makes three-body forces among three quarks. Since the hyper central potential depends only on the hyper radius, therefore, the Cornell potential which is a combination of the Coulombic-like term plus a linear confining term is considered as the potential for interaction between quarks. In our work, in solving the Schrodinger equation with the Cornell potential, the Nikiforov–Uvarov method employed, and the analytic eigen-energies and eigen-functions obtained. By using the obtained eigen-functions, the transition amplitudes calculated. We show that our results in the range Q^2> 2GeV^2 lead to an overall better agreement with the experimental data in comparison with the other three non-relativistic quark models.
基金Supported by the China Scholarship Councilthe Hanjiang Scholar Project of Shaanxi University of Technology
文摘The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the modified equations of motion. Next, using novel transformations, we solve the equation of motion and report the exact analytical solutions.
基金supported by the Ministry of Education of Singapore(Grant No.R146-000-196-112)National Natural Science Foundation of China(Grant No.91430103)
文摘We present several numerical methods and establish their error estimates for the discretization of the nonlinear Dirac equation （NLDE） in the nonrelativistic limit regime, involving a small dimensionless parameter 0 〈 ε〈〈1 which is inversely proportional to the speed of light. In this limit regime, the solution is highly oscillatory in time, i.e., there are propagating waves with wavelength O（ ε^2） and O（1） in time and space, respectively. We begin with the conservative Crank-Nicolson finite difference （CNFD） method and establish rigorously its error estimate which depends explicitly on the mesh size h and time step τ- as well as the small parameter 0 〈 ε≤1 Based on the error bound, in order to obtain ＇correct＇ numerical solutions in the nonrelativistic limit regime, i.e., 0 〈 ε≤1 , the CNFD method requests the ε-scalability： τ- = O（ε3） and h = O（√ε）. Then we propose and analyze two numerical methods for the discretization of NLDE by using the Fourier spectral discretization for spatial derivatives combined with the exponential wave integrator and time- splitting technique for temporal derivatives, respectively. Rigorous error bounds for the two numerical methods show that their ε-scalability is improved to τ = O（ε2） and h = O（1） when 0 〈 ε 〈〈 1. Extensive numerical results are reported to confirm our error estimates.
基金Supported by National Natural Science Foundation of China(11405268,11647113,11705034)
文摘A thorough study reveals that the only key parameter forψ(J/ψ,ψ')polarization at hadron colliders is the ratio〈Oψ(3S1[8])〉/〈Oψ(3P0[8])〉angle,if the velocity scaling rule holds.A slight variation of this parameter results in substantial change of theψpolarization.We find that with equally good description of the yield data,this parameter can vary significantly.Fitting the yield data is therefore incapable of determining this parameter,and consequently,of determining theψpolarization.We provide a universal approach to fixing the long-distance matrix elements(LDMEs)for J/ψandψ'production.Further,with the existing data,we implement this approach,obtain a favorable set of the LDMEs,and manage to reconcile the charmonia production and polarization experiments,except for two sets of CDF data on J/ψpolarization.
文摘Using the scale evolution of nuclear parton distributions,the contribution of color-octet heavy quarkonium production mechanism to the P + Fe → J/ψ + γ + X process in calculated and discussed.Comparing our theoretical results with the future experimental data,the color-octet heavy quarkonium production mechanism can be examined.
文摘The neutrinos of the early universe evolved from a relativistic phase at very early times to a massive particle behavior at later times.First,the kinetic energy of neutrinos is relativistic,and as a result,neutrinos can be described as massless particles.As the Universe expands,the temperature drops and the kinetic energy decreases,and the neutrinos turn into a non-relativistic phase with a non-negligible mass.In this paper,we first put constraints on the total mass of neutrinos.Then we investigate the effect of neutrinos on the CMB power spectrum,P(k),in the case of massless and massive neutrinos using the publicly available Boltzmann code CAMB and we prove that when neutrino coupled to scalar field the CMB power spectrum has a little shift,which means that the power spectrum of CMB is greatly affected by the background energy density and the accelerated expansion of the Universe.Furthermore,we investigate the effect of perturbed quintessence on this spectrum and find that the highest peaks of this spectrum are shifted to smaller scales.Also,we estimate the Deceleration-Acceleration(DA)redshift transition(z_(da))using the coupling canonical scalar field with neutrinos.For Pantheon data we obtain z_(da)=0.7±0.05 and for CC data z_(da)=0.68±0.03.In the presence of neutrinos the DA redshift transition is z_(da)=0.42±0.03 for Pantheon data and z_(da)=0.49±0.05 for CC data.These results indicate that neutrinos can affect this phase transition.The results obtained in this article show that when the mass of neutrinos increases,the value of the background energy density increases,resulting in a higher power spectrum peak.Also,by examining the effect of coupling neutrinos to dark energy,we find that the transition occurs at lower redshift.
文摘In this paper, a quantum mechanical Green’s function for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator (qo) to the harmonic oscillator (ho);second [2], the integration of the classical action function for the quartic oscillator. Here an equivalent form for the quartic oscillator action function in terms of harmonic oscillator variables is derived in order to facilitate the derivation of the quartic oscillator Green’s Function, namely in fixing its amplitude.
文摘A method of Foldy-Wouthuysen transformation for relativistic spin-1/2 particles in external fields is proposed;in the present work the basic properties of the Dirac hamiltonian in the FW representation in the noncommutative phase-space are investigated and the Schrödinger-Pauli equation is found, knowing that the used methods for extracting the full phase-space noncommutative Dirac equation are, the Bopp-shift linear translation method, and the Moyal-Weyl product (*-product).
基金support received from the brazilian funding agencies FAPESP(contract 12/50984-4)support from Generalitat Valenciana in the Program Santiago Grisolia(Exp.GRISOLIA/2015/005)
文摘We use a non-relativistic model to study the spectroscopy of a tetraquark composed of [cc]■ in a diquark-antidiquark configuration.By numerically solving the Schr?dinger equation with a Cornell-inspired potential,we separate the four-body problem into three two-body problems.Spin-dependent terms(spin-spin,spin-orbit and tensor)are used to describe the splitting structure of the ■ spectrum and are also extended to the interaction between diquarks.Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained.We find that the spin-dependent interaction is sizable in the diquark-antidiquark system,despite the heavy diquark mass,and also that the diquark has a finite size if treated in the same way as the ■ systems.We find that the lowest S-wave T 4c tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs,while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds.Finally,we repeat the calculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks.This might be relevant to the study of exotic charmonium in the quark-gluon plasma.The T 4c states could be investigated in the forthcoming experiments at the LHC and BelleⅡ.
基金China Postdoctoral Science Foundation (20070420735)
文摘We have studied Z+(4430)as a D*D1 molecule from the quark model,state mixing effect is considered by solving the coupled channel Schrdinger equation numerically. More precise measurements of Z+(4430)mass and width,partial wave analysis are helpful to understand its structure. If it lies below the D*D1 threshold,molecule interpretation with JP=1-is favored,and JP=0-can not be ruled out. Otherwise Z+(4430)may be a virtual state with JP=2-. The analogous heavy flavor mesons Z+bb and Z++bc are considered as well,and the masses predicted in our model are in agreement with the predictions from the potential model and QCD sum rule.
基金Supported by the National Natural Science Foundation of China(11875071,11975029)the China Postdoctoral Science Foundation(2018M631234)。
文摘We demonstrate that the recently proposed soft gluon factorization(SGF)is equivalent to the nonrelativistic QCD(NRQCD)factorization for heavy quarkonium production or decay,which means that,for any given process,these two factorization theories are either both valid or both violated.We use two methods to arrive at this conclusion.In the first method,we apply the two factorization theories to the physical process J/ψ→e^+e^-.Our explicit calculation shows that both SGF and NRQCD can correctly reproduce the low energy physics of full QCD,and the two factorizations are thus equivalent.In the second method,by using equations of motion,we successfully deduce SGF from NRQCD effective field theory.By identifying SGF with NRQCD factorization,we establish relations between the two factorization theories and prove the generalized Gremm-Kapustin relation as a byproduct.Compared with the NRQCD factorization,the advantage of SGF is that it resums the series of relativistic corrections originating from kinematic effects to all powers,yielding better convergence of the relativistic expansion.
基金Supported in part by the Fundamental Research Funds for the Central Universities(FRF-BR-19-001A)the National Natural Science Foundation of China(11975028)
文摘We study the contributions of intermediate bottomonium-like Zb states and the bottom meson loops in the heavy quark spin flip transitionsγ(4 S)→hb(1 P,2 P)π+π-.Depending on the constructive or destructive interferences between the Zb-exchange and the bottom meson loops mechanisms,we predict two possible branching ratios for each process:BRγ(4 S)→hb(1 P)π+π-≈(1.20.40.8×10^-6)or(0.5-0.20.5×10^-6),and BRγ(4 S)→(2 P)π+π-≈(7.1-1.1+1.7×10^-10)or(2.4-0.10.2×10^-10)).The contribution of the bottom meson loops is found to be considerably larger than that of the Zbexchange in the T(4 S)→hb(1 P)ππtransitions,while its decay rates are not comparable to those of heavy quark spin conservedγ(4 S)→γ(1 S,2 S)ππprocesses.We also predict the contribution of the charm meson loops in the branch fractions ofΨ(3 S,4 S)→hc(1 P)ππ.
基金Supported in part by the Natural Science Foundation of China (12265010)the Project of Guizhou Provincial Department of Education (KY[2021]030)
文摘Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect production of theΞbc andΞbb baryons via the Z-boson decay process Z→Ξbo+b+Q with a Q=(c,b)quark under the NRQCD factorization approach.After considering the contibution from the diquark states(be)PSil3/6,<bc)[^(1)Sol3/6,(bb)[^(3)Sol6,and(bb)[3S1l3,the calculated branching fractions are B(Z-→Ξbe+X)=3.595×10^(-5)and B(Z→Ξbb+X)=1.213×10^(-6).Furthermore,theΞbe andΞbb production events are predicted to be of the order of 104 and 103 at the LHC collider,and the order of 107 and 106 for the CEPC collider.We then estimate the produc tion ratio for Z→c2(bb)→Ξbc+X withΞbc→Λ^(+)_(c)in Z-boson decay,that is,R(Z→cc→Ξ0bc+X)~0(10^(-6))br and R(Z→bb→Ξbc+X)~0(10^(-5)),respectively.Finally,we present the differential decay widths ofΞbc andΞbb with respect to 823 and z distributions and analyze the uncertainties.
基金Supported by the National Natural Science Foundation of China (12005060)。
文摘The decay constants of the low lying S-wave B_(c)mesons,i.e.B_(c)(nS) and B_(c)^(*)(nS) with n ≤3,are calculated in the nonrelativistic quark model.The running coupling of the strong interaction is taken into account,and the uncertainties due to varying parameters and losing Lorentz covariance are considered carefully.As a byproduct,the decay constants of the low lying S-wave charmonium and bottomium states are given in the appendixes.
