量子色动力学(Quantum Chromodynamics,QCD)相图结构和相变临界点是高能物理理论和实验的研究热点。相对论重离子碰撞是探索QCD相图结构、寻找QCD相变临界点的有力工具。美国布鲁克海文国家实验室的相对论重离子对撞机(Relativistic Hea...量子色动力学(Quantum Chromodynamics,QCD)相图结构和相变临界点是高能物理理论和实验的研究热点。相对论重离子碰撞是探索QCD相图结构、寻找QCD相变临界点的有力工具。美国布鲁克海文国家实验室的相对论重离子对撞机(Relativistic Heavy Ion Collider,RHIC)是目前世界上进行高能重离子碰撞的大型实验装置之一,其中的STAR(Solenoidal Tracker at RHIC)实验致力于高温高密条件下夸克胶子等离子体(Quark Gluon Plasma,QGP)性质以及QCD相结构的实验研究。本文着重介绍近年来RHIC-STAR能量扫描实验中运用守恒荷高阶矩和轻核产生寻找QCD相变临界点的研究进展,最后将对高重子密度区QCD相结构的未来研究做出展望。展开更多
A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different...A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different from the traditional Peccei–Quinn approach.Neither new particle nor extra symmetry is introduced,and the role of the Peccei–Quinn axion is played by a quasiparticle arising from the phase of the quark condensate,dubbed as axionic excitation.The derivative of this excitation field is decomposed into a regular part and a singular part,and the latter contains vorticity from the string configuration.A hidden gauge symmetry is revealed in this decomposition and vorticity is represented by an emergent gauge field associated with anomalies.These components,together with the anomaly-inflow mechanism,complete the effective Lagrangian description for the axionic QCD string.展开更多
The sign of higher-order multiplicity fluctuations is a very important parameter for exploring QCD phase transitions.The kurtosis of the net-baryon is typically negative in simulations of the dynamics of the conserved...The sign of higher-order multiplicity fluctuations is a very important parameter for exploring QCD phase transitions.The kurtosis of the net-baryon is typically negative in simulations of the dynamics of the conserved net-baryon density near the QCD critical point.This paper considers the effects of finite size on multiplicity fluctuations with equilibrium critical fluctuations.It is found that the multiplicity fluctuations(or the magnitude of the correlation function D_(ij))are dramatically suppressed with decreasing system size when the size of the system is small compared with the correlation length,which is the so-called acceptance dependence.Consequently,the small correlation function of the small system size results in the magnitude of the negative contribution(~D_(ij)^(4))in the four-point correlation function dominating the positive term(~D_(ij)^(5)),and this finite-size effect induces a dip structure near the QCD critical point.展开更多
We study vacuum of QCD in this work.The structure of non-local quark vacuum condensate,values ofvarious local quark and gluon vacuum condensates,quark-gluon mixed vacuum condensate,quark and gluon virtualityin QCD vac...We study vacuum of QCD in this work.The structure of non-local quark vacuum condensate,values ofvarious local quark and gluon vacuum condensates,quark-gluon mixed vacuum condensate,quark and gluon virtualityin QCD vacuum state,quark dynamical mass and susceptibility of QCD vacuum state to external field are predicted byuse of the solutions of Dyson Schwinger equations in'rainbow'approximation with a modeling gluon propagator andthree different sets of quark-quark interaction parameters.Our theoretical predictions are in good agreement with thecorrespondent empirical values used widely in literature,and many other theoretical calculations.The quark propagatorand self-energy functions are also obtained from the numerical solutions of Dyson-Schwinger equations.This work iscentrally important for studying non-perturbative QCD,and has many important applications both in particle andnuclear physics.展开更多
能量扫描理论合作组(Beam Energy Scan Theory Collaboration,BEST)的目标是建立一个可以描述美国相对论重离子对撞机(Relativistic Heavy-Ion Collider,RHIC)上第二期能量扫描实验的动力学框架。该实验有可能找到强相互作用相图上的临...能量扫描理论合作组(Beam Energy Scan Theory Collaboration,BEST)的目标是建立一个可以描述美国相对论重离子对撞机(Relativistic Heavy-Ion Collider,RHIC)上第二期能量扫描实验的动力学框架。该实验有可能找到强相互作用相图上的临界点。本文总结自2016年起,BEST合作组取得重要进展,并对未来探索中高密度区相图做了展望。展开更多
In this paper,we present an overview on recent progress in studies of QCD at finite temperature and densities within the functional renormalization group(fRG)approach.The f RG is a nonperturbative continuum field appr...In this paper,we present an overview on recent progress in studies of QCD at finite temperature and densities within the functional renormalization group(fRG)approach.The f RG is a nonperturbative continuum field approach,in which quantum,thermal and density fluctuations are integrated successively with the evolution of the renormalization group(RG)scale.The f RG results for the QCD phase structure and the location of the critical end point(CEP),the QCD equation of state(EoS),the magnetic EoS,baryon number fluctuations confronted with recent experimental measurements,various critical exponents,spectral functions in the critical region,the dynamical critical exponent,etc,are presented.Recent estimates of the location of the CEP from first-principle QCD calculations within f RG and Dyson-Schwinger equations,which pass through lattice benchmark tests at small baryon chemical potentials,converge in a rather small region at baryon chemical potentials of about 600 MeV.A region of inhomogeneous instability indicated by a negative wave function renormalization is found withμ_(B)■420 MeV.It is found that the non-monotonic dependence of the kurtosis of the net-proton number distributions on the beam collision energy observed in experiments could arise from the increasingly sharp crossover in the regime of low collision energy.展开更多
文摘量子色动力学(Quantum Chromodynamics,QCD)相图结构和相变临界点是高能物理理论和实验的研究热点。相对论重离子碰撞是探索QCD相图结构、寻找QCD相变临界点的有力工具。美国布鲁克海文国家实验室的相对论重离子对撞机(Relativistic Heavy Ion Collider,RHIC)是目前世界上进行高能重离子碰撞的大型实验装置之一,其中的STAR(Solenoidal Tracker at RHIC)实验致力于高温高密条件下夸克胶子等离子体(Quark Gluon Plasma,QGP)性质以及QCD相结构的实验研究。本文着重介绍近年来RHIC-STAR能量扫描实验中运用守恒荷高阶矩和轻核产生寻找QCD相变临界点的研究进展,最后将对高重子密度区QCD相结构的未来研究做出展望。
基金supported by the Natural Science Foundation of Fujian Province(Grant No.2022J011130)the Research Starting Grant from Minjiang University(Grant No.30804317)。
文摘A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different from the traditional Peccei–Quinn approach.Neither new particle nor extra symmetry is introduced,and the role of the Peccei–Quinn axion is played by a quasiparticle arising from the phase of the quark condensate,dubbed as axionic excitation.The derivative of this excitation field is decomposed into a regular part and a singular part,and the latter contains vorticity from the string configuration.A hidden gauge symmetry is revealed in this decomposition and vorticity is represented by an emergent gauge field associated with anomalies.These components,together with the anomaly-inflow mechanism,complete the effective Lagrangian description for the axionic QCD string.
基金supported by the National Natural Science Foundation of China(No.12305143)the China Postdoctoral Science Foundation(No.2023M731467).
文摘The sign of higher-order multiplicity fluctuations is a very important parameter for exploring QCD phase transitions.The kurtosis of the net-baryon is typically negative in simulations of the dynamics of the conserved net-baryon density near the QCD critical point.This paper considers the effects of finite size on multiplicity fluctuations with equilibrium critical fluctuations.It is found that the multiplicity fluctuations(or the magnitude of the correlation function D_(ij))are dramatically suppressed with decreasing system size when the size of the system is small compared with the correlation length,which is the so-called acceptance dependence.Consequently,the small correlation function of the small system size results in the magnitude of the negative contribution(~D_(ij)^(4))in the four-point correlation function dominating the positive term(~D_(ij)^(5)),and this finite-size effect induces a dip structure near the QCD critical point.
基金National Natural Science Foundation of China under Grant Nos.10647002 and 10565001the Natural Science Foundation of Guangxi under Grant Nos.0575020,0542042,and 0481030
文摘We study vacuum of QCD in this work.The structure of non-local quark vacuum condensate,values ofvarious local quark and gluon vacuum condensates,quark-gluon mixed vacuum condensate,quark and gluon virtualityin QCD vacuum state,quark dynamical mass and susceptibility of QCD vacuum state to external field are predicted byuse of the solutions of Dyson Schwinger equations in'rainbow'approximation with a modeling gluon propagator andthree different sets of quark-quark interaction parameters.Our theoretical predictions are in good agreement with thecorrespondent empirical values used widely in literature,and many other theoretical calculations.The quark propagatorand self-energy functions are also obtained from the numerical solutions of Dyson-Schwinger equations.This work iscentrally important for studying non-perturbative QCD,and has many important applications both in particle andnuclear physics.
文摘能量扫描理论合作组(Beam Energy Scan Theory Collaboration,BEST)的目标是建立一个可以描述美国相对论重离子对撞机(Relativistic Heavy-Ion Collider,RHIC)上第二期能量扫描实验的动力学框架。该实验有可能找到强相互作用相图上的临界点。本文总结自2016年起,BEST合作组取得重要进展,并对未来探索中高密度区相图做了展望。
基金supported by the National Natural Science Foundation of China under Grant No.12175030
文摘In this paper,we present an overview on recent progress in studies of QCD at finite temperature and densities within the functional renormalization group(fRG)approach.The f RG is a nonperturbative continuum field approach,in which quantum,thermal and density fluctuations are integrated successively with the evolution of the renormalization group(RG)scale.The f RG results for the QCD phase structure and the location of the critical end point(CEP),the QCD equation of state(EoS),the magnetic EoS,baryon number fluctuations confronted with recent experimental measurements,various critical exponents,spectral functions in the critical region,the dynamical critical exponent,etc,are presented.Recent estimates of the location of the CEP from first-principle QCD calculations within f RG and Dyson-Schwinger equations,which pass through lattice benchmark tests at small baryon chemical potentials,converge in a rather small region at baryon chemical potentials of about 600 MeV.A region of inhomogeneous instability indicated by a negative wave function renormalization is found withμ_(B)■420 MeV.It is found that the non-monotonic dependence of the kurtosis of the net-proton number distributions on the beam collision energy observed in experiments could arise from the increasingly sharp crossover in the regime of low collision energy.
