Restriction on the form of quark anomalous magnetic moment from lattice QCD results

TL;DR

This paper investigates how different models of the quark anomalous magnetic moment influence the chiral phase transition under magnetic fields, using lattice QCD results to identify the most consistent form.

Contribution

It compares three forms of quark AMM and shows that a quadratic dependence on chiral condensate aligns well with lattice QCD results.

Findings

A constant quark AMM induces a first-order phase transition.

A quark AMM proportional to the chiral condensate reverses its sign.

A quadratic quark AMM matches lattice QCD results for chiral condensate behavior.

Abstract

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.