Static magnetic susceptibility in finite-density SU(2) lattice gauge theory

TL;DR

This study investigates the magnetic susceptibility of SU(2) lattice gauge theory with dynamical fermions at finite chemical potential, revealing paramagnetic behavior that intensifies with temperature and chemical potential, especially in the diquark condensation phase.

Contribution

It provides the first detailed analysis of static magnetic susceptibility in SU(2) lattice gauge theory at finite density, highlighting paramagnetic responses across different regimes.

Findings

Paramagnetic behavior observed in both deconfined and confined phases.

Paramagnetic response increases with temperature and chemical potential.

Maximum response occurs in the diquark condensation phase.

Abstract

We study static magnetic susceptibility $\chi(T, \mu)$ in $SU(2)$ lattice gauge theory with $N_f = 2$ light flavours of dynamical fermions at finite chemical potential $\mu$. Using linear response theory we find that $SU(2)$ gauge theory exhibits paramagnetic behavior in both the high-temperature deconfined regime and the low-temperature confining regime. Paramagnetic response becomes stronger at higher temperatures and larger values of the chemical potential. For our range of temperatures $0.727 \leq T/T_c \leq 2.67$, the first coefficient of the expansion of $\chi(T, \mu)$ in even powers of $\mu/T$ around $\mu=0$ is close to that of free quarks and lies in the range $(2 \ldots 5) \cdot 10^{-3}$. The strongest paramagnetic response is found in the diquark condensation phase at $\mu > m_{\pi}/2$.