The Study On Quark-Hadron Phase Transition At Finite Isospin Chemical Potential

Atomic is consisted by nucleus and electrons,the radius of atomic nucleus is 1/500 of the atomic radius,but it is dominant in the atomic mass,then the density of the nucleus is very high,only white neutron star,black holes and other high density stars can achieve this density.The nucleus can be gathered in such a small space and is not easy to be separated,because there is a strong interaction between the nucleons,quantum chromodynamics(QCD)is mainly used in the study of this strong interaction in particle physics.QCD is based on the non-abelian gause symmetry,which is used to describe the strong interaction between the quarks.It has a very complicated phase structure,such as the hadron phase,QGP(quark gluon plasma)phase,the color superconductivity phase.The principle of the phase transition is the change of the symmetry of the system,such as:chiral phase transition,color superconductivity phase transition,π superfluid phase transition and so on.An interesting topic in QCD is to study the phase structure and to determine the phase boundary and the critical point.In this paper we use QHD model and NJL model to study the temperature and density dependence of the phase boundary at finite temperature and finite isospin chemical potential.Firstly,we use the NJL model lagrangian in the relativistic mean field approximation condition to get the thermodynamic potential of the multiparticle system which is composed of quark,and the energy gap equation is obtained.Then the equation of state of the nuclear field can be obtained by using the QHD model,and the mass of the nuclear and the pressure can be obtained under the approximation of mean field.Finally,according to the phase equilibrium conditions between the quark phase and the hadron phase,the phase transition line can be obtained and analyzed.