Deconfinement critical point of lattice QCD with $N_{\mathrm{f}}=2$ Wilson fermions

Abstract

The $\mathrm{SU}(3)$ pure gauge theory exhibits a first-order thermal deconfinement transition due to spontaneous breaking of its global $Z_3$ center symmetry. When heavy dynamical quarks are added, this symmetry is broken explicitly and the transition weakens with decreasing quark mass until it disappears at a critical point. We compute the critical hopping parameter and the associated pion mass for lattice QCD with $N_f=2$ degenerate standard Wilson fermions on $N_{\tau }\in \{6,8,10\}$ lattices, corresponding to lattice spacings $a=0.12\mathrm{fm}$, $a=0.09\mathrm{fm}$, $a=0.07\mathrm{fm}$, respectively. Significant cut-off effects are observed, with the first-order region growing as the lattice gets finer. While current lattices are still too coarse for a continuum extrapolation, we estimate $m_{\pi }^c\approx 4\mathrm{GeV}$ with a remaining systematic error of $\sim 20\%$. Our results allow to assess the accuracy of the LO and NLO hopping expanded fermion determinant used in the literature for various purposes. We also provide a detailed investigation of the statistics required for this type of calculation, which is useful for similar investigations of the chiral transition.

Comments: 12 pages, 6 figures, minor changes to match the version published in PRD