In this paper,we review recent highlights in heavy-ion collisions and proton–proton collisions at top energies from STAR experiment at the Relativistic Heavy Ion Collider(RHIC) with key contributions from Chinese gro...In this paper,we review recent highlights in heavy-ion collisions and proton–proton collisions at top energies from STAR experiment at the Relativistic Heavy Ion Collider(RHIC) with key contributions from Chinese groups,including the quark–gluon plasma bulk properties,electromagnetic probes,heavy flavor and jets,antimatter hyper-nucleus,nuclear structure,global polarization,and nucleon spin structure.These data serve as important ingredients in the physics of quantum chromodynamics.展开更多
The Cooling-Storage-Ring External-target Experiment(CEE)at the Heavy Ion Research Facility in Lanzhou(HIRFL)is designed to study the properties of nuclear matter created in heavy-ion collisions at beam energies from a...The Cooling-Storage-Ring External-target Experiment(CEE)at the Heavy Ion Research Facility in Lanzhou(HIRFL)is designed to study the properties of nuclear matter created in heavy-ion collisions at beam energies from a few hundred MeV/u up to 1 GeV/u.It aims to facilitate research on the quantum chromodynamics(QCD)phase structure in the high-baryondensity region.Collective flow is a fundamental observable in heavy-ion collision experiments,providing information on the bulk properties of the produced matter.Although the standard event plane method has been widely used to measure collective flow,it is still important to validate and optimize this method for the CEE spectrometer.In this paper,we study the experimental procedures for measuring directed flow in^(238)U+^(238)U collisions at 500 MeV/u,using event planes reconstructed by Multi-Wire Drift Chamber and Zero Degree Calorimeter,respectively.Jet AA Microscopic(JAM)transport generator is used to generate events,and the detector response is simulated by the CEE Fast Simulation(CFS)package.Finally,the optimal kinematic region for proton directed flow measurements is discussed for the future CEE experiment.展开更多
Heavy-ion collisions(HICs)is a unique experimental tool for investigating the properties of nuclear matter under extreme conditions in the laboratory.At HIRFL-CSR energies,HICs can create nuclear matter with 2-3 times...Heavy-ion collisions(HICs)is a unique experimental tool for investigating the properties of nuclear matter under extreme conditions in the laboratory.At HIRFL-CSR energies,HICs can create nuclear matter with 2-3 times the saturation density(ρ_(0)).The HIRFL-CSR external-target experiment(CEE)is a large-acceptance spectrometer designed to explore frontier topics in high-energy nuclear physics,such as the QCD phase structure and nuclear matter equation of states.In this letter,we introduce simulation and analysis software for the CEE experiment(CeeROOT).Based on the CEE conceptual design and CeeROOT software,the configurations of its subdetectors were optimized by considering foreseeable physical constraints.The final detector layout of the CEE spectrometer and its acceptances were validated through simulations of U+U collisions at 500 MeV/u and pp collisions at 2.8 GeV,which demonstrated that the CEE experiment will serve as a detector with wide acceptance and multi-particle identification capabilities for studying high-energy nuclear physics topics at HIRFL-CSR energies with pp,pA,and A A collisions.展开更多
An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.Thi...An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.展开更多
本文利用CR-39固体核径迹探测器对400 A MeV能区范围内的^(12)C、^(40)Ar、^(56)Fe、^(84)Kr射弹分别作用于Al、 C、 CH_(2)靶的电荷拾取反应截面进行了实验研究,探索在400 A MeV能区重离子电荷拾取反应截面与射弹核大小的依赖关系,为...本文利用CR-39固体核径迹探测器对400 A MeV能区范围内的^(12)C、^(40)Ar、^(56)Fe、^(84)Kr射弹分别作用于Al、 C、 CH_(2)靶的电荷拾取反应截面进行了实验研究,探索在400 A MeV能区重离子电荷拾取反应截面与射弹核大小的依赖关系,为此能区的电荷拾取反应机制研究提供实验依据。通过分别利用幂函数和线性函数关系式拟合电荷拾取反应截面与射弹核质量的数据关系,发现幂函数的幂次拟合参数b在-0.01~0.71之间,这种对于射弹核质量A_(P)的依赖关系,与在更高束流能量更重射弹核观察到的结果不同;线性函数的斜率拟合参数β在-0.004~0.24之间,此结果在一定程度上证实电荷拾取反应过程应为边缘及表面反应过程的集体贡献。展开更多
The challenge in searching for fundamental symmetry violation.Neutrinoless double-beta(0νββ)decay represents one of the most profound tests of fundamental symmetries in nature.This hypothetical nuclear process,in w...The challenge in searching for fundamental symmetry violation.Neutrinoless double-beta(0νββ)decay represents one of the most profound tests of fundamental symmetries in nature.This hypothetical nuclear process,in which two neutrons simultaneously decay into two protons with the emission of two electrons but no neutrinos,would demonstrate that lepton number is not conserved and confirm that neutrinos are their own antiparticles(Majorana particles).The observation of 0νββdecay would provide crucial insights into the absolute neutrino mass scale and could illuminate the origin of matter-antimatter asymmetry in the universe.展开更多
The heavy quarks present in the quark-gluon plasma(QGP)can act as a probe of relativistic heavy ion collisions as they retain the memory of their interaction history.In a previous study,a stochastic Schrödinger e...The heavy quarks present in the quark-gluon plasma(QGP)can act as a probe of relativistic heavy ion collisions as they retain the memory of their interaction history.In a previous study,a stochastic Schrödinger equation(SSE)has been applied to describe the evolution of heavy quarks,where an external field with random phases is used to simulate the thermal medium.In this work,we study the connection between the SSE and the Boltzmann transport equation(BE)approach in the Keldysh Green’s function formalism.By comparing the Green’s function of the heavy quark from the SSE and the Keldysh Green’s functions leading to the Boltzmann equation,we demonstrate that the SSE is consistent with the Boltzmann equation in the weak coupling limit.We subsequently confirm their consistency through numerical calculations.展开更多
The validity of the isobaric multiplet mass equation(IMME)is of foundamental importance due to the basic concept of isospin.Recently,a serious breakdown was found in the A=54,T=3,isospin septet,the largest isospin sys...The validity of the isobaric multiplet mass equation(IMME)is of foundamental importance due to the basic concept of isospin.Recently,a serious breakdown was found in the A=54,T=3,isospin septet,the largest isospin system where the validity of IMME have been tested up to now.Inspired by this work,I revist the mass of some isobaric analogue states with the help of recent results from advanced mass measurement experiment.It is found that the IMME holds well in A=50 and 46 isospin septet and the coefficients of IMME also follow the systematic trends.Mass excess value for^(50)Ni and^(46)Fe,is predicted to be-3932(20)keV and 898(67)keV,respectively.展开更多
Investigations into the distribution of neutron and proton densities were conducted within the Skyrme-Hartree-Fock-Bogoliubov(SHFB)framework.It was observed that nucleon orbitals with lower angular quantum numbers are...Investigations into the distribution of neutron and proton densities were conducted within the Skyrme-Hartree-Fock-Bogoliubov(SHFB)framework.It was observed that nucleon orbitals with lower angular quantum numbers are predominantly located inside the nucleus,whereas those with higher angular quantum numbers tend to be distributed more towards the outer regions.Additionally,this study reveals that the difference in the neutron skins of Ru and Zr can be attributed to the distinct contributions of neutron and proton orbitals.Our findings may introduce a novel approach to studying the distribution of nucleon orbitals through relativistic isobaric collisions.展开更多
In this paper we evaluate typical values of magnetic energy and electromagnetic angular momentum of atomic nuclei with very simple scenarios,for the first time.We point out possible situations in which magnetic energy...In this paper we evaluate typical values of magnetic energy and electromagnetic angular momentum of atomic nuclei with very simple scenarios,for the first time.We point out possible situations in which magnetic energy and angular momentum might play essential roles in nuclear physics.展开更多
We study the production of the X(6900)in the ultra-peripheral heavy ion collisions at the LHC energy region.The potential quantum numbers of X(6900)could be 0^(±+)and 2^(±+).We find that the transverse momen...We study the production of the X(6900)in the ultra-peripheral heavy ion collisions at the LHC energy region.The potential quantum numbers of X(6900)could be 0^(±+)and 2^(±+).We find that the transverse momentum and the polar angle distributions of X(6900)can be used to distinguish these four potential quantum numbers.These characteristic distributions originate from linearly polarized photons emitted by relativistic nuclei and can be measured by further LHC experiments.展开更多
The search for the chiral magnetic effect(CME) in relativistic heavy-ion collisions(HICs) is challenged by significant background contamination. We present a novel deep learning approach based on a U-Net architecture ...The search for the chiral magnetic effect(CME) in relativistic heavy-ion collisions(HICs) is challenged by significant background contamination. We present a novel deep learning approach based on a U-Net architecture to time-reversely unfold the dynamics of CME-related charge separation, enabling the reconstruction of the physics signal across the entire evolution of HICs. Trained on the events simulated by a multi-phase transport model with different cases of CME settings, our model learns to recover the charge separation based on final-state transverse momentum distributions at either the quark–gloun plasma freeze-out or hadronic freeze-out. This devises a methodological tool for the study of CME and underscores the promise of deep learning approaches in retrieving physics signals in HICs.展开更多
基金supported in part by the National Key Research and Development Program of China (Grant No.2022YFA1604900)the National Natural Science Foundation of China (Grant No.12575145)。
文摘In this paper,we review recent highlights in heavy-ion collisions and proton–proton collisions at top energies from STAR experiment at the Relativistic Heavy Ion Collider(RHIC) with key contributions from Chinese groups,including the quark–gluon plasma bulk properties,electromagnetic probes,heavy flavor and jets,antimatter hyper-nucleus,nuclear structure,global polarization,and nucleon spin structure.These data serve as important ingredients in the physics of quantum chromodynamics.
基金supported in part by the National Key R&D Program of China(No.2024YFA1610700)the National Natural Science Foundation of China(No.12475147)。
文摘The Cooling-Storage-Ring External-target Experiment(CEE)at the Heavy Ion Research Facility in Lanzhou(HIRFL)is designed to study the properties of nuclear matter created in heavy-ion collisions at beam energies from a few hundred MeV/u up to 1 GeV/u.It aims to facilitate research on the quantum chromodynamics(QCD)phase structure in the high-baryondensity region.Collective flow is a fundamental observable in heavy-ion collision experiments,providing information on the bulk properties of the produced matter.Although the standard event plane method has been widely used to measure collective flow,it is still important to validate and optimize this method for the CEE spectrometer.In this paper,we study the experimental procedures for measuring directed flow in^(238)U+^(238)U collisions at 500 MeV/u,using event planes reconstructed by Multi-Wire Drift Chamber and Zero Degree Calorimeter,respectively.Jet AA Microscopic(JAM)transport generator is used to generate events,and the detector response is simulated by the CEE Fast Simulation(CFS)package.Finally,the optimal kinematic region for proton directed flow measurements is discussed for the future CEE experiment.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34030000)the National Natural Science Foundation of China(Nos.11927901 and 12475133)+1 种基金the Youth Team Program in Basic Research Fields Stably Supported by the Chinese Academy of Sciences(No.YSBR-088)the Western Light Project of the Chinese Academy of Sciences。
文摘Heavy-ion collisions(HICs)is a unique experimental tool for investigating the properties of nuclear matter under extreme conditions in the laboratory.At HIRFL-CSR energies,HICs can create nuclear matter with 2-3 times the saturation density(ρ_(0)).The HIRFL-CSR external-target experiment(CEE)is a large-acceptance spectrometer designed to explore frontier topics in high-energy nuclear physics,such as the QCD phase structure and nuclear matter equation of states.In this letter,we introduce simulation and analysis software for the CEE experiment(CeeROOT).Based on the CEE conceptual design and CeeROOT software,the configurations of its subdetectors were optimized by considering foreseeable physical constraints.The final detector layout of the CEE spectrometer and its acceptances were validated through simulations of U+U collisions at 500 MeV/u and pp collisions at 2.8 GeV,which demonstrated that the CEE experiment will serve as a detector with wide acceptance and multi-particle identification capabilities for studying high-energy nuclear physics topics at HIRFL-CSR energies with pp,pA,and A A collisions.
文摘An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.
文摘本文利用CR-39固体核径迹探测器对400 A MeV能区范围内的^(12)C、^(40)Ar、^(56)Fe、^(84)Kr射弹分别作用于Al、 C、 CH_(2)靶的电荷拾取反应截面进行了实验研究,探索在400 A MeV能区重离子电荷拾取反应截面与射弹核大小的依赖关系,为此能区的电荷拾取反应机制研究提供实验依据。通过分别利用幂函数和线性函数关系式拟合电荷拾取反应截面与射弹核质量的数据关系,发现幂函数的幂次拟合参数b在-0.01~0.71之间,这种对于射弹核质量A_(P)的依赖关系,与在更高束流能量更重射弹核观察到的结果不同;线性函数的斜率拟合参数β在-0.004~0.24之间,此结果在一定程度上证实电荷拾取反应过程应为边缘及表面反应过程的集体贡献。
文摘The challenge in searching for fundamental symmetry violation.Neutrinoless double-beta(0νββ)decay represents one of the most profound tests of fundamental symmetries in nature.This hypothetical nuclear process,in which two neutrons simultaneously decay into two protons with the emission of two electrons but no neutrinos,would demonstrate that lepton number is not conserved and confirm that neutrinos are their own antiparticles(Majorana particles).The observation of 0νββdecay would provide crucial insights into the absolute neutrino mass scale and could illuminate the origin of matter-antimatter asymmetry in the universe.
文摘The heavy quarks present in the quark-gluon plasma(QGP)can act as a probe of relativistic heavy ion collisions as they retain the memory of their interaction history.In a previous study,a stochastic Schrödinger equation(SSE)has been applied to describe the evolution of heavy quarks,where an external field with random phases is used to simulate the thermal medium.In this work,we study the connection between the SSE and the Boltzmann transport equation(BE)approach in the Keldysh Green’s function formalism.By comparing the Green’s function of the heavy quark from the SSE and the Keldysh Green’s functions leading to the Boltzmann equation,we demonstrate that the SSE is consistent with the Boltzmann equation in the weak coupling limit.We subsequently confirm their consistency through numerical calculations.
文摘The validity of the isobaric multiplet mass equation(IMME)is of foundamental importance due to the basic concept of isospin.Recently,a serious breakdown was found in the A=54,T=3,isospin septet,the largest isospin system where the validity of IMME have been tested up to now.Inspired by this work,I revist the mass of some isobaric analogue states with the help of recent results from advanced mass measurement experiment.It is found that the IMME holds well in A=50 and 46 isospin septet and the coefficients of IMME also follow the systematic trends.Mass excess value for^(50)Ni and^(46)Fe,is predicted to be-3932(20)keV and 898(67)keV,respectively.
文摘Investigations into the distribution of neutron and proton densities were conducted within the Skyrme-Hartree-Fock-Bogoliubov(SHFB)framework.It was observed that nucleon orbitals with lower angular quantum numbers are predominantly located inside the nucleus,whereas those with higher angular quantum numbers tend to be distributed more towards the outer regions.Additionally,this study reveals that the difference in the neutron skins of Ru and Zr can be attributed to the distinct contributions of neutron and proton orbitals.Our findings may introduce a novel approach to studying the distribution of nucleon orbitals through relativistic isobaric collisions.
文摘In this paper we evaluate typical values of magnetic energy and electromagnetic angular momentum of atomic nuclei with very simple scenarios,for the first time.We point out possible situations in which magnetic energy and angular momentum might play essential roles in nuclear physics.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant Nos.2020B0301030008 and 2023A1515010416)the National Natural Science Foundation of China(Grant Nos.12375073,12275091,12147128,and 12035007).
文摘We study the production of the X(6900)in the ultra-peripheral heavy ion collisions at the LHC energy region.The potential quantum numbers of X(6900)could be 0^(±+)and 2^(±+).We find that the transverse momentum and the polar angle distributions of X(6900)can be used to distinguish these four potential quantum numbers.These characteristic distributions originate from linearly polarized photons emitted by relativistic nuclei and can be measured by further LHC experiments.
基金supported by the National Natural Science Foundation of China (Grant Nos.12147101 and 12325507)the National Key Research and Development Program of China (Grant No.2022YFA1604900)+4 种基金the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2020B0301030008 for S.G.and G.M.)the CUHK-Shenzhen university development fund (Grant Nos.UDF01003041 and UDF03003041)Shenzhen Peacock Fund (Grant No.2023TC0179 for K.Z.)the RIKEN TRIP initiative (RIKEN Quantum),JSPS KAKENHI (Grant No.25H01560)JST-BOOST (Grant No.JPMJBY24H9 for L.W.)。
文摘The search for the chiral magnetic effect(CME) in relativistic heavy-ion collisions(HICs) is challenged by significant background contamination. We present a novel deep learning approach based on a U-Net architecture to time-reversely unfold the dynamics of CME-related charge separation, enabling the reconstruction of the physics signal across the entire evolution of HICs. Trained on the events simulated by a multi-phase transport model with different cases of CME settings, our model learns to recover the charge separation based on final-state transverse momentum distributions at either the quark–gloun plasma freeze-out or hadronic freeze-out. This devises a methodological tool for the study of CME and underscores the promise of deep learning approaches in retrieving physics signals in HICs.
