The geometry of fireballs in relativistic heavy ion collisions is approximated by a static box,which is infinite in two directions while finite in the other direction.The critical temperature of deconfinement phase tr...The geometry of fireballs in relativistic heavy ion collisions is approximated by a static box,which is infinite in two directions while finite in the other direction.The critical temperature of deconfinement phase transition is calculated explicitly in the MIT bag model at vanishing baryon density.It is found that the critical temperature shifts to a value higher than that in an unconstrained space.展开更多
Fluctuations of dilepton production from two photon interactionsγγ→l^+l^-are studied in semicentral and peripheral nuclear collisions.Based on the Weizsacker-Williams approach,electromagnetic(EM)fields generated by...Fluctuations of dilepton production from two photon interactionsγγ→l^+l^-are studied in semicentral and peripheral nuclear collisions.Based on the Weizsacker-Williams approach,electromagnetic(EM)fields generated by moving nuclear charges are approximated as quasi-real photons.As fluctuating EM fields in each collision event are hard to be measured directly in experiments due to its short lifetime,we study the dilepton photoproduction with fluctuating EM fields,which are crucial for the EM fields induced chiral and charged particle evolutions,and calculate the relative standard deviation of the dilepton mass spectrum with the event-by-event fluctuating nuclear charge distributions.This fluctuation effect becomes smaller in more peripheral collisions where the shift of proton positions is implicit for EM fields outside the nucleus.The uncertainty of effective impact parameter△b on the standard deviation is also studied,and its effect is around one-third of the effect of nuclear charge fluctuations when△b is taken as^1 fm.展开更多
Thermal quantities,including the the entropy density and gluon spectrum,of quark matter within a box that is finite in the longitudinal direction are calculated using a bag model.Under the assumption of entropy conser...Thermal quantities,including the the entropy density and gluon spectrum,of quark matter within a box that is finite in the longitudinal direction are calculated using a bag model.Under the assumption of entropy conservation,the corresponding gluon dissociation rate of J/ψis studied.It reaches a maximum at a certain longitudinal size L_(m),below which the suppression is weak even if the temperature becomes higher than that without the finite size effect,and above which the dissociation rate approaches to the thermodynamic limit gradually with increasing longitudinal size of the fireball.展开更多
This work uses the Boltzmann transport model to study the thermal production of J/ψ and ψ（2S） in the quark gluon plasma（QGP） produced by （sNN）1/2=5.02 TeV Pb-Pb collisions.The J/ψ nuclear modification factors...This work uses the Boltzmann transport model to study the thermal production of J/ψ and ψ（2S） in the quark gluon plasma（QGP） produced by （sNN）1/2=5.02 TeV Pb-Pb collisions.The J/ψ nuclear modification factors are studied in detail alongside the mechanisms of primordial production and the recombination of charm and anti-charm quarks in the thermal medium.The ψ（2S） binding energy is much smaller in the hot medium compared to the ground state;thus,ψ（2S） with middle to low pT can be thermally regenerated in the later stages of QGP expansions,enabling ψ（2S） to inherit larger collective flows from the bulk medium.We quantitatively study the nuclear modification factors of both J/ψ and ψ（2S） in different centralities and transverse momentum bins for （sNN）1/2=5.02 TeV PbPb collisions.展开更多
By solving two body Dirac equations with potentials at finite temperature,we calculate the dissociation temperature T_(d) of B_(c) mesons in quark-gluon plasma.It is found that T_(d) becomes higher with the relativist...By solving two body Dirac equations with potentials at finite temperature,we calculate the dissociation temperature T_(d) of B_(c) mesons in quark-gluon plasma.It is found that T_(d) becomes higher with the relativistic correction than the T_(d) from the Schrodinger equation.Both the short range interaction and the constant term of the potential at the long-range scale have a contribution to the shift of T_(d),while the spin interaction is negligible.展开更多
Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics(QCD),leading to the suppression of quarkonium production in rel...Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics(QCD),leading to the suppression of quarkonium production in relativistic heavy-ion collisions.Owing to the small charm/anti-charm(cc)pair production number in proton-nucleus(pA)collisions,the correlation between different cc pairs is negligible,which makes the Schrödinger equation viable for tracking the evolution of only one cc pair.We employ the time-dependent Schrödinger equation with an in-medium cc potential to study the evolution of charmonium wave functions in a hydrodynamic-like QCD medium produced in pA collisions.We explore different parametrizations of real and imaginary parts of the cc potential and calculate the nuclear modification factors(R_(pA))of J/ψ and ψ(2S)in √s_(NN)=5.02 TeV energy p-Pb collisions at the Large Hadron Collider(LHC).Comparing strong and weak screening scenarios with experimental data in this approach,we arrive at the conclusion that color screening is weak at temperatures close to the deconfined phase transition.Moreover,the imaginary part of the potential is crucial in describing the experimental data,which is consistent with widely studied semi-classical approaches,where dissociation rates are essential.展开更多
By adopting the adiabatic assumption in the cooling process,we discuss a novel mechanism ofΥ(1S)suppression that occurs due to the fast heating process at the early stage of the fireball,instead of its finite decay w...By adopting the adiabatic assumption in the cooling process,we discuss a novel mechanism ofΥ(1S)suppression that occurs due to the fast heating process at the early stage of the fireball,instead of its finite decay width in a finite temperature medium generated by heavy ion collisions.We calculate the transition probability after the fast heating dissociation as a function of the temperature of the medium and the nuclear modification factor in central collisions and find that the suppression is not negligible at RHIC,even if the width ofΥ(1S)becomes zero.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.11547043 and 11705125)the“Qinggu”Project of Tianjin University(Grant No.1701)。
文摘The geometry of fireballs in relativistic heavy ion collisions is approximated by a static box,which is infinite in two directions while finite in the other direction.The critical temperature of deconfinement phase transition is calculated explicitly in the MIT bag model at vanishing baryon density.It is found that the critical temperature shifts to a value higher than that in an unconstrained space.
基金supported by NSFC Grant No.11705125,11547043the Sino-Germany(CSC-DAAD)Postdoc Scholarshipsupport by the AI grant of SAMSON AG,Frankfurt.
文摘Fluctuations of dilepton production from two photon interactionsγγ→l^+l^-are studied in semicentral and peripheral nuclear collisions.Based on the Weizsacker-Williams approach,electromagnetic(EM)fields generated by moving nuclear charges are approximated as quasi-real photons.As fluctuating EM fields in each collision event are hard to be measured directly in experiments due to its short lifetime,we study the dilepton photoproduction with fluctuating EM fields,which are crucial for the EM fields induced chiral and charged particle evolutions,and calculate the relative standard deviation of the dilepton mass spectrum with the event-by-event fluctuating nuclear charge distributions.This fluctuation effect becomes smaller in more peripheral collisions where the shift of proton positions is implicit for EM fields outside the nucleus.The uncertainty of effective impact parameter△b on the standard deviation is also studied,and its effect is around one-third of the effect of nuclear charge fluctuations when△b is taken as^1 fm.
基金supported by the National Natural Science Foundation of China(Grant No.12175165)。
文摘Thermal quantities,including the the entropy density and gluon spectrum,of quark matter within a box that is finite in the longitudinal direction are calculated using a bag model.Under the assumption of entropy conservation,the corresponding gluon dissociation rate of J/ψis studied.It reaches a maximum at a certain longitudinal size L_(m),below which the suppression is weak even if the temperature becomes higher than that without the finite size effect,and above which the dissociation rate approaches to the thermodynamic limit gradually with increasing longitudinal size of the fireball.
基金Supported by NSFC(11705125)Sino-Germany(CSC-DAAD)Postdoc Scholarship
文摘This work uses the Boltzmann transport model to study the thermal production of J/ψ and ψ（2S） in the quark gluon plasma（QGP） produced by （sNN）1/2=5.02 TeV Pb-Pb collisions.The J/ψ nuclear modification factors are studied in detail alongside the mechanisms of primordial production and the recombination of charm and anti-charm quarks in the thermal medium.The ψ（2S） binding energy is much smaller in the hot medium compared to the ground state;thus,ψ（2S） with middle to low pT can be thermally regenerated in the later stages of QGP expansions,enabling ψ（2S） to inherit larger collective flows from the bulk medium.We quantitatively study the nuclear modification factors of both J/ψ and ψ（2S） in different centralities and transverse momentum bins for （sNN）1/2=5.02 TeV PbPb collisions.
基金Supported by the National Natural Science Foundation of China (NSFC)(12175165)。
文摘By solving two body Dirac equations with potentials at finite temperature,we calculate the dissociation temperature T_(d) of B_(c) mesons in quark-gluon plasma.It is found that T_(d) becomes higher with the relativistic correction than the T_(d) from the Schrodinger equation.Both the short range interaction and the constant term of the potential at the long-range scale have a contribution to the shift of T_(d),while the spin interaction is negligible.
基金Supported by the National Natural Science Foundation of China (NSFC)(12175165, 11705125)support from U.S. Department of Energy,Office of Science,Office of Nuclear Physics,(DE-FG88ER40388)support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through the CRC-TR 211’Strong-interaction matter under extreme conditions’–project number 315477589–TRR 211
文摘Color screening and parton inelastic scattering modify the heavy-quark antiquark potential in mediums consisting of particles from quantum chromodynamics(QCD),leading to the suppression of quarkonium production in relativistic heavy-ion collisions.Owing to the small charm/anti-charm(cc)pair production number in proton-nucleus(pA)collisions,the correlation between different cc pairs is negligible,which makes the Schrödinger equation viable for tracking the evolution of only one cc pair.We employ the time-dependent Schrödinger equation with an in-medium cc potential to study the evolution of charmonium wave functions in a hydrodynamic-like QCD medium produced in pA collisions.We explore different parametrizations of real and imaginary parts of the cc potential and calculate the nuclear modification factors(R_(pA))of J/ψ and ψ(2S)in √s_(NN)=5.02 TeV energy p-Pb collisions at the Large Hadron Collider(LHC).Comparing strong and weak screening scenarios with experimental data in this approach,we arrive at the conclusion that color screening is weak at temperatures close to the deconfined phase transition.Moreover,the imaginary part of the potential is crucial in describing the experimental data,which is consistent with widely studied semi-classical approaches,where dissociation rates are essential.
基金Supported by the NSFC (11547043, 11705125)the “Qinggu” project (1701, 40110) of Tianjin University
文摘By adopting the adiabatic assumption in the cooling process,we discuss a novel mechanism ofΥ(1S)suppression that occurs due to the fast heating process at the early stage of the fireball,instead of its finite decay width in a finite temperature medium generated by heavy ion collisions.We calculate the transition probability after the fast heating dissociation as a function of the temperature of the medium and the nuclear modification factor in central collisions and find that the suppression is not negligible at RHIC,even if the width ofΥ(1S)becomes zero.
