Phase diagram of chiral quark matter: color and electrically neutral Fulde-Ferrell phase

TL;DR

This paper explores the phase diagram of charge and color neutral two-flavor quark matter, highlighting the presence of inhomogeneous Fulde-Ferrell phases at low temperatures and their astrophysical relevance.

Contribution

It introduces the phase diagram including FF phases within the NJL model, showing their significance in the matter composition of compact stars.

Findings

FF phase exists at low temperatures below 5 MeV

Critical temperature for 2SC to unpaired transition is 20-30 MeV

Matter in mature stars likely in FF-like superconducting state

Abstract

The phase diagram of charge and color neutral two-flavor color superconducting quark matter is studied including the homogeneous two-flavor superconductor (2SC) and the inhomogeneous Fulde-Ferrell (FF) phases within the Nambu-Jona-Lasinio model. The low-temperature domain T < 5 MeV of the phase diagram contains the FF phase, which borders at high temperatures to the 2SC phase. The critical temperature of phase transition from the 2SC to the unpaired state is in the range 20-30 MeV. We derive the equation of state of matter and its composition and show that matter in mature compact stars should be in the inhomogeneous FF-like superconducting state. We briefly discuss the astrophysical implications of such a phase in compact stars.