The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vec...The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vector pion-photon transition distribution amplitudes are examined,and the results meet the desired properties.Our study involves sum rule and polynomiality condition.The vector and axial vector pion-photon transition form factors that are present in theπ^(+)→γe^(+)νprocess are the first Mellin moments of the pion-photon transition distribution amplitudes.The vector transition form factor originates from the internal structure of hadrons,the axial current can be coupled to a pion,this pion is virtual,and its contribution will be present independently of the external hadrons.The kaon transition form factors are similar.The vector form factor's value at zero momentum transfer is determined by the axial anomaly,while this is not the case for the axial one.The vector and axial form factors,as well as the neutral pion vector form factor F_(πγγ)(t),are depicted.According to our findings,the pion axial transition form factor is harder than the vector transition form factor and harder than the electromagnetic form factor.We also discuss the link betweenπ−γandγ−πtransitions distribution amplitudes.展开更多
Conserved charge fluctuations can be used to probe the phase structure of strongly interacting nuclear matter in relativistic heavy-ion collisions. To obtain the characteristic signatures of the conserved charge fluct...Conserved charge fluctuations can be used to probe the phase structure of strongly interacting nuclear matter in relativistic heavy-ion collisions. To obtain the characteristic signatures of the conserved charge fluctuations for the quantum chromodynamics(QCD) phase transition, we study the susceptibilities of dense quark matter up to eighth order in detail, using an effective QCD-based model. We studied two cases, one with the QCD critical end point(CEP) and one without owing to an additional vector interaction term. The higher order susceptibilities display rich structures near the CEP and show sign changes as well as large fluctuations. These can provide us information about the presence and location of the CEP. Furthermore, we find that the case without the CEP also shows a similar sign change pattern, but with a relatively smaller magnitude compared with the case with the CEP. Finally, we conclude that higher order susceptibilities of conserved charge can be used to probe the QCD phase structures in heavyion collisions.展开更多
Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating...Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating LCDAs on a quantum computer by applying a recently proposed quantum algorithm,with staggered fermions,to the simulation of the LCDA in the(1+1)-dimensional Nambu-Jona-Lasinio(NJL)model on classical hardware.The agreement between the result from the classical simulation of the quantum algorithm and that from exact diagonalization justifies the proposed quantum algorithm.We find that the resulting LCDA in the NJL model exhibits features shared with the LCDAs obtained from the QCD.展开更多
In this study, we investigate the mass spectra of π and σ mesons at finite chemical potential using theself-consistent NJL model and the Fierz-transformed interaction Lagrangian. The model introduces an arbitrary pa...In this study, we investigate the mass spectra of π and σ mesons at finite chemical potential using theself-consistent NJL model and the Fierz-transformed interaction Lagrangian. The model introduces an arbitrary parameterα to reflect the weights of the Fierz-transformed interaction channels. We show that, when α exceeds a certainthreshold value, the chiral phase transition transforms from a first-order one to a smooth crossover, which is evidentfrom the behaviors of the chiral condensates and meson masses. Additionally, at a high chemical potential, the smallerthe value of α, the higher the masses of the π and σ mesons. Moreover, the Mott and dissociation chemical potentialsincrease with the increase in α. Thus, the meson mass emerges as a valuable experimental observable for determiningthe value of α and investigating the properties of the chiral phase transition in dense QCD matter.展开更多
We discuss the sign and energy dependence of second to tenth order susceptibilities of the baryon number,charge number, and strangeness for the analysis of critical conditions in heavy ion collisions in the LHC and RH...We discuss the sign and energy dependence of second to tenth order susceptibilities of the baryon number,charge number, and strangeness for the analysis of critical conditions in heavy ion collisions in the LHC and RHIC by applying a modified Nambu-Jona-Lasinio model. This model is fitted to the quark condensate of the lattice QCD result at finite temperature and zero baryon chemical potential. The presence of a critical point made these susceptibilities deviate considerably from a Hadron-Resonance-Gas model that shows no criticality. The sign, magnitude, and energy dependence of these higher order fluctuations hint towards the existence and location of a critical point that could be discovered in future heavy ion collision experiments.展开更多
The effective Lagrangian of a finite volume system should, in principle, depend on the system size. In the framework of the Nambu-Jona-Lasinio(NJL) model, by considering the influence of quark feedback on the effectiv...The effective Lagrangian of a finite volume system should, in principle, depend on the system size. In the framework of the Nambu-Jona-Lasinio(NJL) model, by considering the influence of quark feedback on the effective coupling, we obtain a modified NJL model so that its Lagrangian depends on the volume. Based on the modified NJL model, we study the influence of finite volume on the chiral phase transition at finite temperature, and find that the pseudo-critical temperature of crossover is much lower than that obtained in the normal NJL model. This clearly shows that the volume dependent effective Lagrangian plays an important role in the chiral phase transitions at finite temperature.展开更多
We investigate nucleon mass splitting at finite isospin chemical potential in the frame of the two-flavour Nambu-Jona-Lasinio model. It is analytically proven that in the phase with explicit isospin symmetry breaking,...We investigate nucleon mass splitting at finite isospin chemical potential in the frame of the two-flavour Nambu-Jona-Lasinio model. It is analytically proven that in the phase with explicit isospin symmetry breaking, the proton mass decreases and the neutron mass increases linearly in the isospin chemical potential.展开更多
The results of comprehensive microscopic optical model calculations are pres-ented for the K<sup>+</sup> scattering from <sup>6</sup>Li,<sup>12</sup>C,<sup>28</sup>Si an...The results of comprehensive microscopic optical model calculations are pres-ented for the K<sup>+</sup> scattering from <sup>6</sup>Li,<sup>12</sup>C,<sup>28</sup>Si and <sup>40</sup>Ca at incident momenta 400-800MeV/c.The unconventional medium effect （i.e.the density-dependent correction forthe K<sup>+</sup>-nucleon scattering amplitude） is considered in two approaches.Both results arein agreement with recent experimental data.The influence of the correction on K<sup>+</sup> scat-tering from different nuclei are discussed in detail and only a weak dependence of thein-medium nucleon“swelling”effects on the mass number of target nuclei is found ex-cept for very light loosely-bound nucleus.展开更多
In a previous work, we proposed an extended Nmnbu-Jona-Lasinio （NJL） model including heavy quark flavors. In this work, we will calculate strong and radiative decays of vector mesons in this extended NJL model, incl...In a previous work, we proposed an extended Nmnbu-Jona-Lasinio （NJL） model including heavy quark flavors. In this work, we will calculate strong and radiative decays of vector mesons in this extended NJL model, including light p, w, K＊, θ and heavy D＊, D＊s, B＊, Bs＊.展开更多
We study the two-color QCD matter with two fundamental quark flavors using the chiral perturbation theory and the Nambu-Jona-Lasinio(NJL)model.The effective Lagrangian is derived in terms of mesons and baryons,i.e.diq...We study the two-color QCD matter with two fundamental quark flavors using the chiral perturbation theory and the Nambu-Jona-Lasinio(NJL)model.The effective Lagrangian is derived in terms of mesons and baryons,i.e.diquarks.The low lying excitations lie in the extended SU(4)flavor symmetry space.We compute the leading order terms of the Lagrangian as a function of the baryon and axial isospin densities.After numerically solving the gap equations in the two-color NJL model,the phase diagram is obtained in the μ−ν5 plane.展开更多
The transport equation for the Nambu-Jona-Lasinio (NJL) model isderived phenomenologically. The finite-temperature effective mass for the quarkis analysed, By means of the Chapman-Enskog method and hydrodynamic ap-pro...The transport equation for the Nambu-Jona-Lasinio (NJL) model isderived phenomenologically. The finite-temperature effective mass for the quarkis analysed, By means of the Chapman-Enskog method and hydrodynamic ap-proach the different transport coefficients for the NJL plasma are calculated tothe first order in the relaxation time.展开更多
The Eigenstate Method has been developed to deduce the fermion propagator with a constant external magnetic field. In general, we find its result is equivalent to other methods and this new method is more convenient,e...The Eigenstate Method has been developed to deduce the fermion propagator with a constant external magnetic field. In general, we find its result is equivalent to other methods and this new method is more convenient,especially when one evaluates the contribution from the infinitesimal imaginary term of the fermion propagator. Using the Eigenstate Method we try to discuss whether the infinitesimal imaginary frequency of the fermion propagator in a strong magnetic field and Lorentz-violating extension of the minimal SU（3）×SU（2）×SU（1） Standard Model could have a significant influence on the dynamical mass. When the imaginary term of the fermion propagator in this model is not trivial（√（α-1）eB/3） 〈 σ 〈（√（α-1）2eB/3）, this model gives a correction to the dynamical mass.When one does not consider the influence from the imaginary term（σ 〉√（α-1）2eB/3）, there is another correction from the conventional term. Under both circumstances, chiral symmetry is broken.展开更多
Based on an extended NJL model including heavy quark flavors, we calculate the form factors of pseudoscalar and vector mesons. After taking into account the vector-meson-dominance effect, which introduces a form facto...Based on an extended NJL model including heavy quark flavors, we calculate the form factors of pseudoscalar and vector mesons. After taking into account the vector-meson-dominance effect, which introduces a form factor correction to the quark vector coupling vertices, the form factors and electric radii of π^＋ and K^＋ pseudo-scalar mesons in the light flavor sector fit the experimental data well. The magnetic moments of the light vector mesons ρ^＋and K^＊＋are comparable with other theoretical calculations. The form factors in the light-heavy flavor sector are presented to compare with future experiments or other theoretical calculations.展开更多
We derive the scalar resonance coupling constants of resonance chiral theory from the extended Nambu Jona-Lasinio model by using heat-kernel expansion.
We propose an extended Nambu-Jona-Lasinio model to include heavy mesons with heavy quark symmetry.The quark current-current interaction is generalized to include the heavy quark currents. In order to comply with the h...We propose an extended Nambu-Jona-Lasinio model to include heavy mesons with heavy quark symmetry.The quark current-current interaction is generalized to include the heavy quark currents. In order to comply with the heavy quark spin symmetry at the heavy quark limit,the dependence of the quark mass on the interaction strength is introduced. The light and heavy pseudo-scalar and vector mesons,their masses and the weak decay constants are calculated in the unified frame.展开更多
We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove...We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove that they are completely equivalent in the imaginary-time and real-time formalisms by separating carefully the imaginary part of the zero-temperature loop integral. It is shown that the same thermal transformation matrix of the matrix propagators for these bound states in the real-time formalism is precisely the one of the matrix propagator for an elementary scalar particle and this fact shows the similarity of thermodynamic property between a composite and elementary scalar particle. The retarded and advanced propagators for these bound states are also given explicitly from the imaginary-time formalism.展开更多
With the two-flavor Nambu–Jona–Lasinio (NJL) model, we carried out a phenomenological study on the chiral phase structure, mesonic properties, and transport properties of momentum-space anisotropic quark matter. To ...With the two-flavor Nambu–Jona–Lasinio (NJL) model, we carried out a phenomenological study on the chiral phase structure, mesonic properties, and transport properties of momentum-space anisotropic quark matter. To calculate the transport coefficients we utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both the distribution function and relaxation time. It was shown that an increase in the anisotropy parameterξmay result in a catalysis of chiral symmetry breaking. The critical endpoint(CEP) is shifted to lower temperatures and larger quark chemical potentials asξincreases, and the impact of momentum anisotropy on the CEP temperature is almost the same as that on the quark chemical potential of the CEP. The meson masses and the associated decay widths also exhibit a significant ξ dependence. It was observed that the temperature behavior of the scaled shear viscosity η/T~3 and scaled electrical conductivity σ/T exhibited a similar dip structure, with the minima of both η/T~3 and σ/T shifting toward higher temperatures with increasing ξ. Furthermore,we demonstrated that the Seebeck coefficient S decreases when the temperature rises and its sign is positive, indicating that the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient S is significantly enhanced with a largeξfor a temperature below the critical temperature.展开更多
The Nambu–Jona-Lasinio(NJL)model is one of the most useful tools for studying non-perturbative strong interactions in matter.Because it is a nonrenormalizable model,the choice of regularization is a subtle issue.In t...The Nambu–Jona-Lasinio(NJL)model is one of the most useful tools for studying non-perturbative strong interactions in matter.Because it is a nonrenormalizable model,the choice of regularization is a subtle issue.In this paper,we discuss one of the general issues regarding regularization in the NJL model,which is whether we need to use regularization for the thermal part by evaluating the quark chiral condensate and thermal properties in the two-flavor NJL model.The calculations in this work include three regularization schemes that contain both gauge covariant and invariant schemes.We found that,regardless of the regularization scheme we choose,it is necessary to use regularization for the thermal part when calculating physical quantities related to the chiral condensate and to not use regularization for the thermal part when calculating physical quantities related to the grand potential.展开更多
In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL model.The self-consistent mean field approximation introduces ...In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL model.The self-consistent mean field approximation introduces a new parameter,α,that cannot be fixed in advance by the mean field approach itself.Due to the lack of experimental data,the parameter,α,is undetermined.Hence,it is regarded as a free parameter and its influence on the chiral phase transition of strong interaction matter is studied based on this self-consistent mean field approximation.αaffects numerous properties of the chiral phase transitions,such as the position of the phase transition point and the order of phase transition.Additionally,increasingαwill decrease the number densities of different quarks and increase the chemical potential at which the number density of the strange quark is non-zero.Finally,we observed thatαaffects the equation of state(EOS)of the quark matter,and the sound velocity can be calculated to determine the stiffness of the EOS,which provides a good basis for studying the neutron star mass-radius relationship.展开更多
We study the mass spectra and decay process of σ and π_(0) mesons under a strong external magnetic field.To achieve this goal,we deduce the thermodynamic potential in a two-flavor,hot and magnetized Nambu-Jona-Lasin...We study the mass spectra and decay process of σ and π_(0) mesons under a strong external magnetic field.To achieve this goal,we deduce the thermodynamic potential in a two-flavor,hot and magnetized Nambu-Jona-Lasinio model.We calculate the energy gap equation through the random phase approximation(RPA).Then we use the Ritus method to calculate the decay triangle diagram and self-energy in the presence of a constant magnetic field B.Our results indicate that the magnetic field has little influence on the mass of π_(0) at low temperatures.However,for quarks andσmesons,their mass clearly changes,which reflects the influence of magnetic catalysis(MC).The presence of a magnetic field accelerates the decay of the meson while the presence of a chemical potential will decrease the decay process.展开更多
基金Supported by the Scientific Research Foundation of Nanjing Institute of Technology(YKJ202352)the Natural Science Foundation of Jiangsu Province,China(BK20191472)the China Postdoctoral Science Foundation(2022M721564)。
文摘The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vector pion-photon transition distribution amplitudes are examined,and the results meet the desired properties.Our study involves sum rule and polynomiality condition.The vector and axial vector pion-photon transition form factors that are present in theπ^(+)→γe^(+)νprocess are the first Mellin moments of the pion-photon transition distribution amplitudes.The vector transition form factor originates from the internal structure of hadrons,the axial current can be coupled to a pion,this pion is virtual,and its contribution will be present independently of the external hadrons.The kaon transition form factors are similar.The vector form factor's value at zero momentum transfer is determined by the axial anomaly,while this is not the case for the axial one.The vector and axial form factors,as well as the neutral pion vector form factor F_(πγγ)(t),are depicted.According to our findings,the pion axial transition form factor is harder than the vector transition form factor and harder than the electromagnetic form factor.We also discuss the link betweenπ−γandγ−πtransitions distribution amplitudes.
基金Supported in part by the National Natural Science Foundation of China(11475085,11535005,11690030,11575069,11221504)the MoST of China 973-Project(2015CB856901)
文摘Conserved charge fluctuations can be used to probe the phase structure of strongly interacting nuclear matter in relativistic heavy-ion collisions. To obtain the characteristic signatures of the conserved charge fluctuations for the quantum chromodynamics(QCD) phase transition, we study the susceptibilities of dense quark matter up to eighth order in detail, using an effective QCD-based model. We studied two cases, one with the QCD critical end point(CEP) and one without owing to an additional vector interaction term. The higher order susceptibilities display rich structures near the CEP and show sign changes as well as large fluctuations. These can provide us information about the presence and location of the CEP. Furthermore, we find that the case without the CEP also shows a similar sign change pattern, but with a relatively smaller magnitude compared with the case with the CEP. Finally, we conclude that higher order susceptibilities of conserved charge can be used to probe the QCD phase structures in heavyion collisions.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022512,12035007,12175016,12005065,12074180)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030008)+3 种基金the Key-Area Research and Development Program of Guangdong Province(Grant No.2019B030330001)the Guangdong Basic and Applied Basic Research Fund(Grant No.2021A1515010317)the Key Project of Science and Technology of Guangzhou(Grant No.2019050001)the National Special Support Program for High-level Talents。
文摘Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating LCDAs on a quantum computer by applying a recently proposed quantum algorithm,with staggered fermions,to the simulation of the LCDA in the(1+1)-dimensional Nambu-Jona-Lasinio(NJL)model on classical hardware.The agreement between the result from the classical simulation of the quantum algorithm and that from exact diagonalization justifies the proposed quantum algorithm.We find that the resulting LCDA in the NJL model exhibits features shared with the LCDAs obtained from the QCD.
基金the Start-up Funding of Jiangsu University(4111190010)the Natural Science Foundation of China(12147103)。
文摘In this study, we investigate the mass spectra of π and σ mesons at finite chemical potential using theself-consistent NJL model and the Fierz-transformed interaction Lagrangian. The model introduces an arbitrary parameterα to reflect the weights of the Fierz-transformed interaction channels. We show that, when α exceeds a certainthreshold value, the chiral phase transition transforms from a first-order one to a smooth crossover, which is evidentfrom the behaviors of the chiral condensates and meson masses. Additionally, at a high chemical potential, the smallerthe value of α, the higher the masses of the π and σ mesons. Moreover, the Mott and dissociation chemical potentialsincrease with the increase in α. Thus, the meson mass emerges as a valuable experimental observable for determiningthe value of α and investigating the properties of the chiral phase transition in dense QCD matter.
基金Supported in part by the MoST of China 973-Project(2015CB856901)the National Natural Science Foundation of China(11475085,11535005,11690030,11575069,11221504,11890711,11861131009)the Fundamental Research Funds for the Central Universities(020414380074,CCNU19QN054)
文摘We discuss the sign and energy dependence of second to tenth order susceptibilities of the baryon number,charge number, and strangeness for the analysis of critical conditions in heavy ion collisions in the LHC and RHIC by applying a modified Nambu-Jona-Lasinio model. This model is fitted to the quark condensate of the lattice QCD result at finite temperature and zero baryon chemical potential. The presence of a critical point made these susceptibilities deviate considerably from a Hadron-Resonance-Gas model that shows no criticality. The sign, magnitude, and energy dependence of these higher order fluctuations hint towards the existence and location of a critical point that could be discovered in future heavy ion collision experiments.
基金Supported by the National Natural Science Foundation of China(11475085,11535005,11690030)the National Major state Basic Research and Development(2016YFE0129300)
文摘The effective Lagrangian of a finite volume system should, in principle, depend on the system size. In the framework of the Nambu-Jona-Lasinio(NJL) model, by considering the influence of quark feedback on the effective coupling, we obtain a modified NJL model so that its Lagrangian depends on the volume. Based on the modified NJL model, we study the influence of finite volume on the chiral phase transition at finite temperature, and find that the pseudo-critical temperature of crossover is much lower than that obtained in the normal NJL model. This clearly shows that the volume dependent effective Lagrangian plays an important role in the chiral phase transitions at finite temperature.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10428510 and 10575058. One of the authors （Chang S.） thanks the High Energy Nuclear Physics Group of Tsinghua University for kind hospitality and Lianyi He and Xuewen Hao for helpful discussions.
文摘We investigate nucleon mass splitting at finite isospin chemical potential in the frame of the two-flavour Nambu-Jona-Lasinio model. It is analytically proven that in the phase with explicit isospin symmetry breaking, the proton mass decreases and the neutron mass increases linearly in the isospin chemical potential.
基金The project supportcd in part by the National Natural Science Foundation of China
文摘The results of comprehensive microscopic optical model calculations are pres-ented for the K<sup>+</sup> scattering from <sup>6</sup>Li,<sup>12</sup>C,<sup>28</sup>Si and <sup>40</sup>Ca at incident momenta 400-800MeV/c.The unconventional medium effect （i.e.the density-dependent correction forthe K<sup>+</sup>-nucleon scattering amplitude） is considered in two approaches.Both results arein agreement with recent experimental data.The influence of the correction on K<sup>+</sup> scat-tering from different nuclei are discussed in detail and only a weak dependence of thein-medium nucleon“swelling”effects on the mass number of target nuclei is found ex-cept for very light loosely-bound nucleus.
文摘In a previous work, we proposed an extended Nmnbu-Jona-Lasinio （NJL） model including heavy quark flavors. In this work, we will calculate strong and radiative decays of vector mesons in this extended NJL model, including light p, w, K＊, θ and heavy D＊, D＊s, B＊, Bs＊.
基金Supported by the NSFC(11605254)Major State Basic Research Development Program in China(2015CB856903)
文摘We study the two-color QCD matter with two fundamental quark flavors using the chiral perturbation theory and the Nambu-Jona-Lasinio(NJL)model.The effective Lagrangian is derived in terms of mesons and baryons,i.e.diquarks.The low lying excitations lie in the extended SU(4)flavor symmetry space.We compute the leading order terms of the Lagrangian as a function of the baryon and axial isospin densities.After numerically solving the gap equations in the two-color NJL model,the phase diagram is obtained in the μ−ν5 plane.
基金The project supported by the Postdoctor Science Foundation the Nuclear Industry Foundation of China
文摘The transport equation for the Nambu-Jona-Lasinio (NJL) model isderived phenomenologically. The finite-temperature effective mass for the quarkis analysed, By means of the Chapman-Enskog method and hydrodynamic ap-proach the different transport coefficients for the NJL plasma are calculated tothe first order in the relaxation time.
基金Supported in part by National Natural Science Foundation of China(11275097,11475085,11535005,11690030)China Postdoctoral Science Foundation(2014M561621)Jiangsu Planned Projects for Postdoctoral Research Funds(1401116C)
文摘The Eigenstate Method has been developed to deduce the fermion propagator with a constant external magnetic field. In general, we find its result is equivalent to other methods and this new method is more convenient,especially when one evaluates the contribution from the infinitesimal imaginary term of the fermion propagator. Using the Eigenstate Method we try to discuss whether the infinitesimal imaginary frequency of the fermion propagator in a strong magnetic field and Lorentz-violating extension of the minimal SU（3）×SU（2）×SU（1） Standard Model could have a significant influence on the dynamical mass. When the imaginary term of the fermion propagator in this model is not trivial（√（α-1）eB/3） 〈 σ 〈（√（α-1）2eB/3）, this model gives a correction to the dynamical mass.When one does not consider the influence from the imaginary term（σ 〉√（α-1）2eB/3）, there is another correction from the conventional term. Under both circumstances, chiral symmetry is broken.
文摘Based on an extended NJL model including heavy quark flavors, we calculate the form factors of pseudoscalar and vector mesons. After taking into account the vector-meson-dominance effect, which introduces a form factor correction to the quark vector coupling vertices, the form factors and electric radii of π^＋ and K^＋ pseudo-scalar mesons in the light flavor sector fit the experimental data well. The magnetic moments of the light vector mesons ρ^＋and K^＊＋are comparable with other theoretical calculations. The form factors in the light-heavy flavor sector are presented to compare with future experiments or other theoretical calculations.
基金The project supported in part by National Natural Science Foundations of China under Grant Nos.10575002 and 10421503
文摘We derive the scalar resonance coupling constants of resonance chiral theory from the extended Nambu Jona-Lasinio model by using heat-kernel expansion.
文摘We propose an extended Nambu-Jona-Lasinio model to include heavy mesons with heavy quark symmetry.The quark current-current interaction is generalized to include the heavy quark currents. In order to comply with the heavy quark spin symmetry at the heavy quark limit,the dependence of the quark mass on the interaction strength is introduced. The light and heavy pseudo-scalar and vector mesons,their masses and the weak decay constants are calculated in the unified frame.
文摘We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove that they are completely equivalent in the imaginary-time and real-time formalisms by separating carefully the imaginary part of the zero-temperature loop integral. It is shown that the same thermal transformation matrix of the matrix propagators for these bound states in the real-time formalism is precisely the one of the matrix propagator for an elementary scalar particle and this fact shows the similarity of thermodynamic property between a composite and elementary scalar particle. The retarded and advanced propagators for these bound states are also given explicitly from the imaginary-time formalism.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (No.2020B0301030008)the Natural Science Foundation of China (No.11935007)the Science and Technology Program of Guangzhou (No.2019050001).
文摘With the two-flavor Nambu–Jona–Lasinio (NJL) model, we carried out a phenomenological study on the chiral phase structure, mesonic properties, and transport properties of momentum-space anisotropic quark matter. To calculate the transport coefficients we utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both the distribution function and relaxation time. It was shown that an increase in the anisotropy parameterξmay result in a catalysis of chiral symmetry breaking. The critical endpoint(CEP) is shifted to lower temperatures and larger quark chemical potentials asξincreases, and the impact of momentum anisotropy on the CEP temperature is almost the same as that on the quark chemical potential of the CEP. The meson masses and the associated decay widths also exhibit a significant ξ dependence. It was observed that the temperature behavior of the scaled shear viscosity η/T~3 and scaled electrical conductivity σ/T exhibited a similar dip structure, with the minima of both η/T~3 and σ/T shifting toward higher temperatures with increasing ξ. Furthermore,we demonstrated that the Seebeck coefficient S decreases when the temperature rises and its sign is positive, indicating that the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient S is significantly enhanced with a largeξfor a temperature below the critical temperature.
基金Supported by the Natural Science Foundation of Jiangsu Province(BK20140523)the start-up funding of Jiangsu University(15JDG042,4111190010)the National Natural Science Foundation of China(11735007)。
文摘The Nambu–Jona-Lasinio(NJL)model is one of the most useful tools for studying non-perturbative strong interactions in matter.Because it is a nonrenormalizable model,the choice of regularization is a subtle issue.In this paper,we discuss one of the general issues regarding regularization in the NJL model,which is whether we need to use regularization for the thermal part by evaluating the quark chiral condensate and thermal properties in the two-flavor NJL model.The calculations in this work include three regularization schemes that contain both gauge covariant and invariant schemes.We found that,regardless of the regularization scheme we choose,it is necessary to use regularization for the thermal part when calculating physical quantities related to the chiral condensate and to not use regularization for the thermal part when calculating physical quantities related to the grand potential.
文摘In this study,we apply a self-consistent mean field approximation of the three-flavor Nambu–Jona-Lasinio(NJL)model and compare it with the two-flavor NJL model.The self-consistent mean field approximation introduces a new parameter,α,that cannot be fixed in advance by the mean field approach itself.Due to the lack of experimental data,the parameter,α,is undetermined.Hence,it is regarded as a free parameter and its influence on the chiral phase transition of strong interaction matter is studied based on this self-consistent mean field approximation.αaffects numerous properties of the chiral phase transitions,such as the position of the phase transition point and the order of phase transition.Additionally,increasingαwill decrease the number densities of different quarks and increase the chemical potential at which the number density of the strange quark is non-zero.Finally,we observed thatαaffects the equation of state(EOS)of the quark matter,and the sound velocity can be calculated to determine the stiffness of the EOS,which provides a good basis for studying the neutron star mass-radius relationship.
基金Supported by the National Natural Science Foundation of China(11735007,11890711,11890710)。
文摘We study the mass spectra and decay process of σ and π_(0) mesons under a strong external magnetic field.To achieve this goal,we deduce the thermodynamic potential in a two-flavor,hot and magnetized Nambu-Jona-Lasinio model.We calculate the energy gap equation through the random phase approximation(RPA).Then we use the Ritus method to calculate the decay triangle diagram and self-energy in the presence of a constant magnetic field B.Our results indicate that the magnetic field has little influence on the mass of π_(0) at low temperatures.However,for quarks andσmesons,their mass clearly changes,which reflects the influence of magnetic catalysis(MC).The presence of a magnetic field accelerates the decay of the meson while the presence of a chemical potential will decrease the decay process.
