The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase stru...The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region.Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions.One of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion collisions.This step is crucial for measuring the collective flow and other reaction-plane-related analyses.In this paper,we illustrate the procedures for event plane determination using the ZDC.Finally,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.展开更多
The transition of strong-interaction matter from the hadronic phase to the quark-gluon plasma phase is a rapid crossover but not a true phase transition in nature.The true phase transition of strong-interaction matter...The transition of strong-interaction matter from the hadronic phase to the quark-gluon plasma phase is a rapid crossover but not a true phase transition in nature.The true phase transition of strong-interaction matter is expected to exist only in certain limits,e.g.chiral limit of massless quarks and etc.In this contribution to CNPC2023 Special Issue we present our recent studies on the true phase transition of strong-interaction matter in the chiral limit of massless quarks as well as its microscopic origin.The study is based on(2+1)-flavor lattice QCD simulations using highly improved staggered fermions,with pion masses ranging from 160 MeV down to 55 MeV.Utilizing a newly proposed method to compute the quark mass derivatives of the Dirac eigenvalue spectrum on the lattice,it is found that the axial U(1)anomaly is still manifested at 1.6T_(c),with a microscopic origin consistent with the dilute instanton gas approximation.Furthermore,based on lattice QCD results and a generalized Banks-Casher relation,it is found that the macroscopic singularity of the chiral phase transition is encoded in the correlation of the Dirac eigenvalue spectrum.Future research directions along these findings are also discussed,including the investigation of the temperature range between T_(c) and 1.6 T_(c) to understand the breakdown of the dilute instanton gas approximation and its connection to the chiral phase transition.展开更多
基金the National Key Research and Development Program of China(Nos.2022YFA1604900 and 2020YFE0202002)the National Natural Science Foundation of China(Nos.12175084,11890710,11890711,11927901)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34030000)Fundamental Research Funds for Central Universities(No.CCNU220N003).
文摘The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region.Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions.One of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion collisions.This step is crucial for measuring the collective flow and other reaction-plane-related analyses.In this paper,we illustrate the procedures for event plane determination using the ZDC.Finally,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.
文摘The transition of strong-interaction matter from the hadronic phase to the quark-gluon plasma phase is a rapid crossover but not a true phase transition in nature.The true phase transition of strong-interaction matter is expected to exist only in certain limits,e.g.chiral limit of massless quarks and etc.In this contribution to CNPC2023 Special Issue we present our recent studies on the true phase transition of strong-interaction matter in the chiral limit of massless quarks as well as its microscopic origin.The study is based on(2+1)-flavor lattice QCD simulations using highly improved staggered fermions,with pion masses ranging from 160 MeV down to 55 MeV.Utilizing a newly proposed method to compute the quark mass derivatives of the Dirac eigenvalue spectrum on the lattice,it is found that the axial U(1)anomaly is still manifested at 1.6T_(c),with a microscopic origin consistent with the dilute instanton gas approximation.Furthermore,based on lattice QCD results and a generalized Banks-Casher relation,it is found that the macroscopic singularity of the chiral phase transition is encoded in the correlation of the Dirac eigenvalue spectrum.Future research directions along these findings are also discussed,including the investigation of the temperature range between T_(c) and 1.6 T_(c) to understand the breakdown of the dilute instanton gas approximation and its connection to the chiral phase transition.
