Study Of Chiral Phase Transition Under Chiral Chemical Potential

The investigation of the phase transition in strongly interacting matter is an important topic in particle physics.It is of great significance for further understanding the properties of the strong interaction and studying phenomena in the early universe,dense stars and relativistic heavy-ion collisions.Quantum chromodynamics(QCD),a fundamental theory describing strong interactions,is an important part of the standard model of particle physics.QCD phase diagram is the key to understand the critical behavior of QCD at finite temperature and chemical potential.From a theoretical point of view,investigating QCD phase diagram requires deal with QCD at low energy region,while considering the strong coupling involved,the calculation is very difficult.Lattice QCD simulations or effective models is the usual approach employed to deal with low-energy strong interactions.The Nambu-Jona-Lasinio(NJL)model is one of the most widely used effective models,which provides a mechanism for spontaneous breaking of chiral symmetry,and is widely used to describe the characteristics of chiral symmetry restoration at finite temperature and/or density.At the high temperature of the quark gluon plasma phase,the gluon configuration with non-zero winding number can be generated at a relatively high probability,thus producing local chiral imbalance,it is convenient to introduce chiral chemical potential,which is coupled to the chiral number of particles.In the lattice simulation,the chiral chemical potential does not produce the sign problem caused by the baryonic chemical potential,allowing the lattice simulation to proceed without difficulty.Therefore,investigating the phase transition of strong matter under the chiral chemical potential is important for a deep understanding of the phase structure of QCD.In this thesis we use a two-flavor NJL model to investigate the impact of the chiral chemical potential on the chiral phase transition at finite temperature,and a uniform external magnetic field is taken into account too.In this research,we use the regularization scheme of the three-dimensional momentum truncation,and by solving the mass gap equation to give the quark effective mass varying with the relevant quantity to obtain the critical point of the phase transition.The results show that the enhancement of the chiral chemical potential leads to the critical chemical potential decreasing and the critical temperature increasing and then decreasing,which reflects the catalytic and reverse catalytic effects of the critical chemical potential on the chiral symmetry breaking;Increasing magnetic field strength can increase the critical temperature,the critical chemical potential and the critical chiral chemical potential,strengthening the chiral symmetry breaking.Furthermore,we also briefly discuss the finite-volume effects.