Fierz-complete NJL model study II: towards the fixed-point and phase structure of hot and dense two-flavor QCD

Understand

Nambu-Jona-Lasinio-type models are often employed as low-energy models for the theory of the strong interaction to analyze its phase structure at finite temperature and quark chemical potential.

• In particular at low temperature and large chemical potential, where the application of fully first-principles approaches is currently difficult at best, this class of models still plays a prominent role to guide our understanding of the dynamics of dense strong-interaction matter.
• In this work, we consider a Fierz-complete version of the Nambu-Jona-Lasinio model with two massless quark flavors and study its renormalization group flow and fixed-point structure at leading order of the derivative expansion of the effective action.
• Sum rules for the various four-quark couplings then allow us to monitor the strength of the breaking of the axial $U_{\rm A}(1)$ symmetry close to and above the phase boundary.