Influence of magnetic fields on the stability and the phase transition of quark matter in the Nambu–Jona–Lasinio model

Abstract

Abstract In the presence of the external magnetic fields, we investigate the stability of quark matter as well as the phase transition in the framework of two flavor Nambu–Jona–Lasinio model. The investigation focuses on the magnetic effects with the fixed coupling constant and the running coupling constant G(B, T) depending on both magnetic field and temperature. The dynamical quark mass can be increased by strong magnetic fields and be reduced by the running coupling constant G(B, T). The baryon number density is also increased by strong magnetic fields but is weakly influenced by the running coupling constant G(B, T). Importantly, the stability can be enhanced by the magnetic fields of a proper strength. While it will be reduced by the much weaker or much stronger magnetic fields. The magnetic-field-dependence in the running coupling constant has slight effect on the stability. Finally, the phase transition and the location of critical end point for both coupling cases are numerically shown.