Chiral Phase Transition Of NJL Model With Chiral Chemical Potential Under Magnetic Field Background

As a fundamental theory to explain the phenomenon of strong interactions,quantum chromodynamics has a very rich phase structure,especially at high temperature and high density conditions,the chiral phase transition and deconfinement phase transition may occur.The non-Abelian nature of QCD leads to its vacuum with multiple topological structures,and under certain conditions imbalance in right-handed and left-handed quarks may be produced,this imbalance can be described by introducing the chiral chemical potential conjugated with the chiral charge.On the other hand,there may be strong magnetic fields in noncentral heavy ion collision experiments,so it is necessary to investigate the effect of magnetic fields on phase transitions of quark matter.Theoretically,lattice QCD based on first-principle numerical simulation is often used to handle low-energy strong interactions,but this method has a sign problem at finite chemical potential,which limits its applicability.Alternatively,phenomenological research is often performed by using various low-energy effective models.The NJL model is one of effective models for dealing with nonperturbative strongly interacting matter and is characterized by a well-described spontaneous breaking of chiral symmetry.In this thesis,we use the two-flavor NJL model which incorporates the chemical potential and the chiral chemical potential investigate the influence of a uniform magnetic field on the critical chiral chemical potential for the chiral phase transition.As usual,the external magnetic field is introduced through a minimal coupling.It is shown that with the increase of the magnetic field both the constituent quark mass and the critical chiral chemical potential become larger.This indicates the magnetic catalytic effect on the spontaneous breaking of the chiral symmetry.In a region close to the critical chiral chemical potential,the constituent mass of the quark decreases monotonically with increasing chiral chemical potential.In addition,the increase in temperature or the chemical potential will lead to the reduction of the critical chiral chemical potential.