Deconfining and Chiral Transitions of Finite-Temperature Quantum Chromodynamics in the Presence of Dynamical Quark Loops

Finite-temperature behavior of quantum chromodynamics is investigated with the Langevin technique including the dynamical quark loops. The deconfining and chiral transitions occur at the same temperature. The strength of transition weakens initially as the quark mass decreases from infinity, but at small quark masses it strengthens again and shows the characteristic of a first-order transition. We estimate the inverse coupling constant at zero quark mass to be ${\beta }_c=\frac{6}{g_c^{}{}_{}{}^2}\simeq 4.9-5.0$ for four flavors on an $8^3$ × 4 lattice.