Restriction on the form of quark anomalous magnetic moment from lattice QCD results
The quark anomalous magnetic moment (AMM) is dynamically generated through the spontaneous chiral symmetry breaking. It has been revealed that even though its exact form is still unknown, the quark AMM is essential to explore quark matter properties and QCD phase structure under external magnetic fields. In this study, we take three different forms of the quark AMM and investigate its influence on the chiral phase transition under magnetic field. In general, a negative quark AMM plays the role as magnetic catalyzer and a positive quark AMM plays the role of magnetic inhibition. It is found that a constant quark AMM drives an unexpected 1st order chiral phase transition; a quark AMM proportional to the chiral condensate gives a flip of the sign on the chiral condensate; and a quark AMM proportional to the square of chiral condensate can produce results of chiral condensate as functions of the temperature and the magnetic field in good agreement with the lattice result.