Studying properties of the SU(2) QCD by lattice field theory methods

TL;DR

This study addresses the SU(2) QCD phase diagram in the $(\mu, T)$ plane by lattice simulations to locate the confinement-deconfinement transition line. The authors employ a tree-level improved Symanzik gauge action with improved staggered fermions, simulate on $N_s=32$ with varying $N_t$ and $0\le a\mu\le 0.2$, and renormalize the Polyakov loop while extracting the static potential from Wilson loops to determine the temperature where $\sigma(T)$ vanishes. They use four observables — the Polyakov loop inflection point, its susceptibility $\chi_P$, the static quark entropy $S_q$, and the string tension $\sigma(T)$ — finding consistent $T_d(\mu)$ trends with a slow variation at small $\mu$ and near-linear decrease at larger $\mu$, and $\mu$-dependent weakening of the transition. Results agree qualitatively with Begun et al. (2022) but show some disagreement with Boz et al. (2019) at higher $\mu$, motivating further high-$\mu$ studies and improved spectral analyses of the thermal potential.

Abstract

We present new results on properties of $SU(2)$ QCD in lattice regularization. Our main goal is to find the transition line confinement - deconfinement in $μ- T$ plane. We compute the Polyakov loop and the string tension to determine this line.

Figures (3)

• Figure 1: Left:The Polyakov loop susceptibility vs. $T$; Right: The static quark entropy vs. $T$. The curves show fits to gaussian function.
• Figure 2: Left: The thermal potential $V_t(r)$ vs. $t$ for $r/a=4$ and 10 computed via eq. (\ref{['eq:Vt']}) (empty symbols) and via eq. (\ref{['eq:bala']}) (filled symbols) at $T=171$ MeV, $\mu=615$ MeV; Right: The thermal potential $V(r)$ at $T=171$ MeV for few values of $\mu$. The lines are fits to eq. (\ref{['eq:Cornell']}) (for low $\mu$) or fits to eq. (\ref{['eq:screened']}) (for high $\mu$).
• Figure 3: Left: The string tension vs. $\mu$ for various $T$; Right: phase diagram