Numerical Study On Mass Effect Of Heavy Quarks Energy Loss By LBT Model

According to the asymptotic freedom and the quark.confinement in quantum chromodynamics,nuclear matter with high temperature and density will turn to a special state which called quark gluon plasma.It is thought that the extreme rela-tivistic heavy ion collision experiment can produce the conditions of high temperature and density,thus producing this new form of matter.In the last two decades,the relativistic heavy ion collider at brookhaven national laboratory in long island,New York,and the large hadron collider at CERN in Europe have carried out extreme relativistic heavy ion collisions to produce the QGP matter and researched it.The research of high temperature and high density quark matter has gradually become one of the important topics in the field of high energy nuclear physics,which helps people to understand the basic structure and laws of the material world,as well as the composition of neutron stars and the early evolution of the big bang.The large transverse momentum partons which producted in the early stage of relativistic heavy ion collisions will through the QGP medium and multiple scattering with the medium partons,and induce radiation gluons at same time,this process called jet quenching.Jet quenching will leads to series of phenomena such as hadronic spectrum depression,anisotropy and correlation of two particles,which can be re-searched by experimental detection.Currently,some phenomenological models have been developed to describe the process of partons in QGP medium in high energy nuclear physics,and to analyze the mechanism and law of energy loss.The Linear Boltzmann Transport model(LBT model)is one of such successful and well known model.The LBT model includes multiple scattering,the medium induce gluon radi-ation and the recoil process of medium.It can describe the propagation and energy loss of partons and jets in QGP medium,and to detailed research the medium modify effect of jet and the media recoil of jets response in heavy ion collisions.This model has become an famous monte carlo model about jet quenching and widely recognized by the international academic community.This article used the LBT model to researched the light partons and heavy quarks energy loss,associated the depression of the production and the nuclear modification factor of partons and jets,we focus on the mass effect of heavy quark energy loss that used numerical analysis,it's beneficial to obtain some important innovative results in the future.we used the hydromechanics to describe the evolution of temperature and density in QGP medium,a non-equilibrium thermodynamic system is used to describe the evolution of partial transportation in medium,and the bremsstrahlung model base on high-twist theory is used to describe the process of gluon radiation which caused Energy loss.The numerical analysis shows that the difference of mass size between different partons made a significant difference between the energy loss in QGP medium.For example,the contributions of quarks with different masses to the nuclear modification factor RAA would be obviously different:the larger the parton mass,the smaller the energy loss,it's the typical Dead Cone effect of heavy quark energy loss.Our numerical analysis also shows that the energy losses of quarks in different mass are close to the same value in the large transverse momentum region,and the energy losses of quarks in different mass tend to be the same at higher collision energies.The mass effect of heavy quarks is so small relative to very high energies that it is almost the same as that of light quarks,this might be why the nuclear modification factors observed are approximately the same as those of heavy and light quarks in LHC more higher energy experiments.In order to further analyze the mass effect of quark energy loss,we also tried to simulate the proton-proton collision with PYTHIA8,and used the anti-kt algorithm provided by Fast Jet to make the jet construction.we analyzed the mass effect in angle distribution of gluons which from bremsstrahlung in vacum,and compared with the Dead Cone effect in experiment,our numerical results accord with the trend of experimental data qualitatively.