The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated sys...The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the LQMD.RMF are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^(-) and π^(+) yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich systems.However, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.展开更多
Traditional particle identification methods face timeconsuming,experience-dependent,and poor repeatability challenges in heavy-ion collisions at low and intermediate energies.Researchers urgently need solutions to the...Traditional particle identification methods face timeconsuming,experience-dependent,and poor repeatability challenges in heavy-ion collisions at low and intermediate energies.Researchers urgently need solutions to the dilemma of traditional particle identification methods.This study explores the possibility of applying intelligent learning algorithms to the particle identification of heavy-ion collisions at low and intermediate energies.Multiple intelligent algorithms,including XgBoost and TabNet,were selected to test datasets from the neutron ion multi-detector for reaction-oriented dynamics(NIMROD-ISiS)and Geant4 simulation.Tree-based machine learning algorithms and deep learning algorithms e.g.TabNet show excellent performance and generalization ability.Adding additional data features besides energy deposition can improve the algorithm’s performance when the data distribution is nonuniform.Intelligent learning algorithms can be applied to solve the particle identification problem in heavy-ion collisions at low and intermediate energies.展开更多
The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements...The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components Px and Py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.展开更多
The thermodynamic properties of charged particles,such as the energy density,pressure,entropy density,particle density,and squared speed of sound at the kinetic freeze-out in the Au+Au collisions from the relativistic...The thermodynamic properties of charged particles,such as the energy density,pressure,entropy density,particle density,and squared speed of sound at the kinetic freeze-out in the Au+Au collisions from the relativistic heavy ion collider (RHIC)beam energy scan program √S_(NN) and in the Cu+Cu collisions at √S_(NN),200 GeV are studied using the thermodynamically consistent Tsallis distribution.The energy density,pressure,and particle density decrease monotonically with the collision energy for the same collision centrality;These properties also decrease monotonically from the central to peripheral collisions at the same collision energy.While the scaled energy densityε∕T^(4) and scaled entropy density s∕T^(3) demonstrate the opposite trend with the collision energy for the same collision centrality.There is a correlation betweenε∕T^(4) and s∕T^(3) at the same centrality.In addition,the squared speed of sound was calculated to determine that all the collision energies share nearly the same value at different collision centralities.展开更多
The data of charged particles produced in proton-proton collisions extracted from Durham particle data group at energy ranges √s = 6.3 - 17 GeV and at 0.9 - 7 TeV are investigated in the framework of Tsallis thermo-s...The data of charged particles produced in proton-proton collisions extracted from Durham particle data group at energy ranges √s = 6.3 - 17 GeV and at 0.9 - 7 TeV are investigated in the framework of Tsallis thermo-statistics and the Vlasov time dynamics. The analysis can describe the experimental data well all-over the considered energies and rapidity intervals. The variation of the collision parameters (chemical potential, entropy index and the time of evolution) is studied and discussed as a function of the final state temperature. According to the obtained result, a scenario, and a script of the time evolution for the particle production is simulated by the pp collision.展开更多
Angular distributions of pious and kaons produced in heavy ion collisions at the low-energy end of high energies (1-2 A GeV) have been investigated by using a multisource ideal gas model. The model covers the expans...Angular distributions of pious and kaons produced in heavy ion collisions at the low-energy end of high energies (1-2 A GeV) have been investigated by using a multisource ideal gas model. The model covers the expansions and movements of the emission sources, and it is related to the collective flows. By using the analytic expression and the Monte Carlo method, the azimuthal and polar angle distributions of mesons are calculated by the model and compared with the experimental data of the KaoS Collaboration.展开更多
We calculate the back-to-back correlation (BBC) functions of relativistic boson-antiboson pairs in high energy heavy ion collisions using the Monte Carlo method. The relativistic effects on the BBC functions of ФФ...We calculate the back-to-back correlation (BBC) functions of relativistic boson-antiboson pairs in high energy heavy ion collisions using the Monte Carlo method. The relativistic effects on the BBC functions of ФФ and K+K pairs are investigated. The investigations indicate that the relativistic effects on the BBC functions of K+K- pairs with large momenta are significant, and the effect is sensitive to the particle freeze-out temperature.展开更多
The transverse momentum distributions of final-state particles produced in collisions at high en-ergies are studied by using a two-component Rayleigh-like distribution.This representation is based on Liu's multisourc...The transverse momentum distributions of final-state particles produced in collisions at high en-ergies are studied by using a two-component Rayleigh-like distribution.This representation is based on Liu's multisource ideal gas model which describes protons and fragments in high energy nucleus-nucleus collisions.The calculated results are in good agreement with the experimental data of Au-Au,Cu-Cu,d-Au,and pp collisions at the relativistic heavy ion collider energies.The experimental particle momentum distributions of p-Be collisions at 6.4,12.3,and 17.5 GeV/c,as well as Au-Au collisions at 1.5 AGeV are well described by a model based on a single Rayleigh-like distribution of particle transverse momenta.展开更多
The Levy-stability of self-affine random cascading model is investigated in some detail. It is found that the Levy-stability indices of cascading process depend upon not only the dynamical fluctuation parameter a but ...The Levy-stability of self-affine random cascading model is investigated in some detail. It is found that the Levy-stability indices of cascading process depend upon not only the dynamical fluctuation parameter a but also the way of shrinking phase space when calculating scaled factorial moments, which propose a quantitative criterion to determine whether the dynamical fluctuation is anisotropic. Besides, the puzzle of Levy-stability violation of NA22 data is comprehensively solved under the hypothesis of anisotropic dynamical fluctuation.展开更多
The yields of fragments produced in the ^60Ni+ ^12C reactions at 80 A and 140 A MeV, and with maximum impact parameters of 1.5, 2 and 7.3 fm at 80 A MeV are calculated by the statistical abrasion-ablation model. The ...The yields of fragments produced in the ^60Ni+ ^12C reactions at 80 A and 140 A MeV, and with maximum impact parameters of 1.5, 2 and 7.3 fm at 80 A MeV are calculated by the statistical abrasion-ablation model. The yields of fragments are analyzed by the isobaric yield ratio (IYR) method to extract the coefficient of symmetry energy to temperature (asym/T ). The incident energy is found to influence asym/T very little. It’s found that asym/T of fragments with the same neutron-excess I = N-Z increases when A increases, while asym/T of isobars decreases when A increases. The asym/T of prefragments is rather smaller than that of the final fragments, and the asym/T of fragments in small impact parameters is smaller than that of the larger impact parameters, which both indicate that asym/T decreases when the temperature increases. The choice of the reference IYRs is found to have influence on the extracted a sym /T of fragments, especially on the results of the more neutron-rich fragments. The surface-symmetry energy coefficient (bs/T ) and the volume-symmetry energy coefficient (bv/T) are also extracted, and the bs/bv is found to coincide with the theoretical results.展开更多
Recent experiments show that Δy,an observable designed to detect the chiral magnetic effect(CME),in small collision systems(p+A) is similar to that in heavy ion collisions(A+A).This introduces a challenge to the exis...Recent experiments show that Δy,an observable designed to detect the chiral magnetic effect(CME),in small collision systems(p+A) is similar to that in heavy ion collisions(A+A).This introduces a challenge to the existence of the CME because it is believed that no azimuthal correlation exists between the orientation of the magnetic field(Φ_(B)) and participant plane(Φ_(2)) in small collision systems.In this work,we introduce three charge density models to describe the inner charge distributions of protons and neutrons and calculate the electric and magnetic fields produced in small p+A collisions at both RHIC and LHC energies.Our results show that the contribution of the single projectile proton is the main contributor to the magnetic field after averaging over all participants.The azimuthal correlation between Φ_(B) and Φ_(2) is small but not vanished.Additionally,owing to the large fluctuation in field strength,the magnetic-field contribution to Δγ may be large.展开更多
The production scale and internal structure of jets produced in high energy collisions were studied using Jetset and Herwig Monte Carlo generators. Two scales were found. One is the jet-development scale, which determ...The production scale and internal structure of jets produced in high energy collisions were studied using Jetset and Herwig Monte Carlo generators. Two scales were found. One is the jet-development scale, which determines the size of the jet developed from a mother-parton. The other is the jet-production scale with which the jets produced are the most consistent with QCD jet-production dynamics and will provide the most reliable dynamical information about their mother-partons.展开更多
The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interact...The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and cal-culate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hq on incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e + e-, pp and AA inter-actions, and the comparison and analysis are carried out between experimental data and QCD predic-tion. The latest results are given in this paper.展开更多
The main objective of this study was to investigate the impact of effective mass splitting on heavy-ion-collision observables.We first analyzed correlations between different nuclear matter parameters obtained from 11...The main objective of this study was to investigate the impact of effective mass splitting on heavy-ion-collision observables.We first analyzed correlations between different nuclear matter parameters obtained from 119 effective Skyrme interaction sets.The values of the correlation coefficients illustrate that the magnitude of effective mass splitting is crucial for tight constraints on the symmetry energy via heavy-ion collisions.The^(86)Kr+^(208)Pb system at beam energies ranging from 25 to 200A MeV was simulated within the framework of the improved quantum molecular dynamics model(ImQMD-Sky).Our calculations show that the slopes of the spectra of ln[Y(n)/Y(p)]and ln[Y(t)/Y(^(3)He)],which are the logarithms of the neutron to proton and triton to helium-3 yield ratios,are directly related to effective mass splitting and can be used to probe the effective mass splitting.展开更多
基金This study was supported by the National Natural Science Foundation ofChina(Nos.12147106,12175072,and 11722546)the Talent Programof South China University of Technology(No.20210115).
文摘The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the LQMD.RMF are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^(-) and π^(+) yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich systems.However, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.
基金This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34030000)the National Key Research and Development Program of China(No.2022YFA1602404)+1 种基金the National Natural Science Foundation(No.U1832129)the Youth Innovation Promotion Association CAS(No.2017309).
文摘Traditional particle identification methods face timeconsuming,experience-dependent,and poor repeatability challenges in heavy-ion collisions at low and intermediate energies.Researchers urgently need solutions to the dilemma of traditional particle identification methods.This study explores the possibility of applying intelligent learning algorithms to the particle identification of heavy-ion collisions at low and intermediate energies.Multiple intelligent algorithms,including XgBoost and TabNet,were selected to test datasets from the neutron ion multi-detector for reaction-oriented dynamics(NIMROD-ISiS)and Geant4 simulation.Tree-based machine learning algorithms and deep learning algorithms e.g.TabNet show excellent performance and generalization ability.Adding additional data features besides energy deposition can improve the algorithm’s performance when the data distribution is nonuniform.Intelligent learning algorithms can be applied to solve the particle identification problem in heavy-ion collisions at low and intermediate energies.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10275042 and 10475054), the Shanxi Provincial Natural Science Foundation (Grant No 20021006), and the Shanxi Provincial 1Foundation for Returned 0verseas Scholars.
文摘The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components Px and Py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.
基金supported in part by the National Natural Science Foundation of China (Nos. 11905120 and 11947416)the Natural Science Foundation of the Sichuan Province (No. 2023NSFSC1322)+1 种基金the United States Department of Energy (#DE-FG02-93ER40773)the NNSA (No. DENA0003841 (CENTAUR))。
文摘The thermodynamic properties of charged particles,such as the energy density,pressure,entropy density,particle density,and squared speed of sound at the kinetic freeze-out in the Au+Au collisions from the relativistic heavy ion collider (RHIC)beam energy scan program √S_(NN) and in the Cu+Cu collisions at √S_(NN),200 GeV are studied using the thermodynamically consistent Tsallis distribution.The energy density,pressure,and particle density decrease monotonically with the collision energy for the same collision centrality;These properties also decrease monotonically from the central to peripheral collisions at the same collision energy.While the scaled energy densityε∕T^(4) and scaled entropy density s∕T^(3) demonstrate the opposite trend with the collision energy for the same collision centrality.There is a correlation betweenε∕T^(4) and s∕T^(3) at the same centrality.In addition,the squared speed of sound was calculated to determine that all the collision energies share nearly the same value at different collision centralities.
文摘The data of charged particles produced in proton-proton collisions extracted from Durham particle data group at energy ranges √s = 6.3 - 17 GeV and at 0.9 - 7 TeV are investigated in the framework of Tsallis thermo-statistics and the Vlasov time dynamics. The analysis can describe the experimental data well all-over the considered energies and rapidity intervals. The variation of the collision parameters (chemical potential, entropy index and the time of evolution) is studied and discussed as a function of the final state temperature. According to the obtained result, a scenario, and a script of the time evolution for the particle production is simulated by the pp collision.
基金Project supported by the National Natural Science Foundation of China(Grant Nos10675077 and 10275042)the Shanxi Provincial Natural Science Foundation of China(Grant No2007011005)the Shanxi Provincial Foundation for Returned Overseas Scholars,China
文摘Angular distributions of pious and kaons produced in heavy ion collisions at the low-energy end of high energies (1-2 A GeV) have been investigated by using a multisource ideal gas model. The model covers the expansions and movements of the emission sources, and it is related to the collective flows. By using the analytic expression and the Monte Carlo method, the azimuthal and polar angle distributions of mesons are calculated by the model and compared with the experimental data of the KaoS Collaboration.
基金Supported by National Natural Science Foundation of China(11275037)
文摘We calculate the back-to-back correlation (BBC) functions of relativistic boson-antiboson pairs in high energy heavy ion collisions using the Monte Carlo method. The relativistic effects on the BBC functions of ФФ and K+K pairs are investigated. The investigations indicate that the relativistic effects on the BBC functions of K+K- pairs with large momenta are significant, and the effect is sensitive to the particle freeze-out temperature.
基金Supported by NSFC (10675077,10975095)Natural Science Foundation of Shanxi Province (2007011005)
文摘The transverse momentum distributions of final-state particles produced in collisions at high en-ergies are studied by using a two-component Rayleigh-like distribution.This representation is based on Liu's multisource ideal gas model which describes protons and fragments in high energy nucleus-nucleus collisions.The calculated results are in good agreement with the experimental data of Au-Au,Cu-Cu,d-Au,and pp collisions at the relativistic heavy ion collider energies.The experimental particle momentum distributions of p-Be collisions at 6.4,12.3,and 17.5 GeV/c,as well as Au-Au collisions at 1.5 AGeV are well described by a model based on a single Rayleigh-like distribution of particle transverse momenta.
基金supported in part by the National Natural Science Foundation of China the DYTF of the state Education Commssion of China and the CGP of Wuhan City.
文摘The Levy-stability of self-affine random cascading model is investigated in some detail. It is found that the Levy-stability indices of cascading process depend upon not only the dynamical fluctuation parameter a but also the way of shrinking phase space when calculating scaled factorial moments, which propose a quantitative criterion to determine whether the dynamical fluctuation is anisotropic. Besides, the puzzle of Levy-stability violation of NA22 data is comprehensively solved under the hypothesis of anisotropic dynamical fluctuation.
基金Supported by National Natural Science Foundation of China (10905017)Program for Innovative Research Team (in Science and Technology) in the Universities of Henan Province (2010IRTSTHN002)Young Teacher Project in Henan Normal University
文摘The yields of fragments produced in the ^60Ni+ ^12C reactions at 80 A and 140 A MeV, and with maximum impact parameters of 1.5, 2 and 7.3 fm at 80 A MeV are calculated by the statistical abrasion-ablation model. The yields of fragments are analyzed by the isobaric yield ratio (IYR) method to extract the coefficient of symmetry energy to temperature (asym/T ). The incident energy is found to influence asym/T very little. It’s found that asym/T of fragments with the same neutron-excess I = N-Z increases when A increases, while asym/T of isobars decreases when A increases. The asym/T of prefragments is rather smaller than that of the final fragments, and the asym/T of fragments in small impact parameters is smaller than that of the larger impact parameters, which both indicate that asym/T decreases when the temperature increases. The choice of the reference IYRs is found to have influence on the extracted a sym /T of fragments, especially on the results of the more neutron-rich fragments. The surface-symmetry energy coefficient (bs/T ) and the volume-symmetry energy coefficient (bv/T) are also extracted, and the bs/bv is found to coincide with the theoretical results.
文摘Recent experiments show that Δy,an observable designed to detect the chiral magnetic effect(CME),in small collision systems(p+A) is similar to that in heavy ion collisions(A+A).This introduces a challenge to the existence of the CME because it is believed that no azimuthal correlation exists between the orientation of the magnetic field(Φ_(B)) and participant plane(Φ_(2)) in small collision systems.In this work,we introduce three charge density models to describe the inner charge distributions of protons and neutrons and calculate the electric and magnetic fields produced in small p+A collisions at both RHIC and LHC energies.Our results show that the contribution of the single projectile proton is the main contributor to the magnetic field after averaging over all participants.The azimuthal correlation between Φ_(B) and Φ_(2) is small but not vanished.Additionally,owing to the large fluctuation in field strength,the magnetic-field contribution to Δγ may be large.
基金Supported by the National Natural Science Foundation of China (Grant Nos.10775056,90503001)
文摘The production scale and internal structure of jets produced in high energy collisions were studied using Jetset and Herwig Monte Carlo generators. Two scales were found. One is the jet-development scale, which determines the size of the jet developed from a mother-parton. The other is the jet-production scale with which the jets produced are the most consistent with QCD jet-production dynamics and will provide the most reliable dynamical information about their mother-partons.
基金the National Natural Science Foundation of China (Grant Nos. 19875019, 10075200) the Natural Science Foundation of Hubei Province.
文摘The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and cal-culate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hq on incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e + e-, pp and AA inter-actions, and the comparison and analysis are carried out between experimental data and QCD predic-tion. The latest results are given in this paper.
基金supported by the National Natural Science Foundation of China(Nos.12275359,11875323,11961141003,U2032145,11890712)the National Key R&D Program of China(No.2018YFA0404404)+1 种基金the Continuous Basic Scientific Research Project(Nos.WDJC-2019-13 and BJ20002501)funding from the China Institute of Atomic Energy(No.YZ222407001301).
文摘The main objective of this study was to investigate the impact of effective mass splitting on heavy-ion-collision observables.We first analyzed correlations between different nuclear matter parameters obtained from 119 effective Skyrme interaction sets.The values of the correlation coefficients illustrate that the magnitude of effective mass splitting is crucial for tight constraints on the symmetry energy via heavy-ion collisions.The^(86)Kr+^(208)Pb system at beam energies ranging from 25 to 200A MeV was simulated within the framework of the improved quantum molecular dynamics model(ImQMD-Sky).Our calculations show that the slopes of the spectra of ln[Y(n)/Y(p)]and ln[Y(t)/Y(^(3)He)],which are the logarithms of the neutron to proton and triton to helium-3 yield ratios,are directly related to effective mass splitting and can be used to probe the effective mass splitting.