Strong coupling lattice study of 1/g2 evolution in phase diagram and baryon mass

We investigate the phase diagram and the baryon mass (MB) in the color SU(Nc = 3) strong coupling lattice QCD with one species of staggered fermions at finite quark chemical potential (μ) and/or finite temperature (T ). In particular, their evolution with the finite coupling (1/g2) is studied in the next to leading order of the strong coupling expansion. We formulate the treatment of the temporal plaquette effects by introducing some new kinds of mean fields, which lead to the suppression of μ and the constituent quark mass (mq). These energy scale modifications cause the following phase diagram evolution: (1) The ratio of the critical value (μc/Tc) becomes closer to the empirical value. (2) As the coupling decreases, the second order transition at zero chemical potential evolves to the first order, and the critical temperature Tc is found to be consistent with lattice Monte-Carlo simulations. The same suppression mechanism of μ also modifies the analytic relation between the baryon mass MB and the critical baryon chemical potential (Ncμc). We show that the ratio Ncμc/MB grows as the coupling decreases, and this trend may be helpful to form the nuclear matter in the current frame work.