Effect of temperature and magnetic field on two-flavor superconducting quark matter

TL;DR

This study explores how temperature and magnetic fields influence two-flavor color superconducting quark matter, revealing complex behaviors like gap oscillations and magnetic catalysis relevant to neutron star cores.

Contribution

It provides a detailed analysis of the interplay between temperature, magnetic field, and superconducting gaps in dense quark matter using the NJL model, highlighting novel effects at high magnetic fields.

Findings

Magnetic field induces anomalous temperature behavior in the gap.

High magnetic fields cause abrupt quenching of the 2SC gap.

Dynamical quark mass exhibits oscillations and magnetic catalysis.

Abstract

We investigate the effect of turning on temperature for the charge neutral phase of two-flavor color superconducting (2SC) dense quark matter in presence of constant external magnetic field. Within the Nambu-Jona-Lasinio model, by tuning the diquark coupling strength, we study the interdependent evolution of the quark Bardeen-Cooper-Schrieffer gap and dynamical mass as functions of temperature and magnetic field. We find that magnetic field $B \gtrsim 0.02$ GeV$^2$ ($10^{18}$ G) leads to anomalous temperature behavior of the gap in the gapless 2SC phase (moderately strong coupling), reminiscent of previous results in the literature found in the limit of weak coupling without magnetic field. The 2SC gap in the strong coupling regime is abruptly quenched at ultrahigh magnetic field due to the mismatched Fermi surfaces of up and down quarks imposed by charge neutrality and oscillation of the gap due to Landau level quantization. The dynamical quark mass also displays strong oscillation and magnetic catalysis at high magnetic field, although the latter effect is tempered by nonzero temperature. We discuss the implications for newly born compact stars with superconducting quark cores.