Confinement/Deconfinement Transition of Large N Gauge Theories with N_f Fundamentals: N_f/N Finite

We consider large N zero-coupling d-dimensional U(N) gauge theories, with N_f matter fields in the fundamental representation on a compact spatial manifold S^{d-1} x time, with N_f/N finite. The Gauss' law constraint induces interactions among the fields, in spite of the zero-coupling. This class of theories undergo a 3rd order deconfinement phase transition at a temperature T_c proportional to the inverse length scale of the compact manifold. The low-temperature phase has a free-energy of {\cal O} (N^2_f), interpreted as that of a gas of (color singlet) mesons and glueballs. The high-temperature (deconfinement) phase has a free energy of order N^2 f (N_f/N, T), which is interpreted as that of a gas of gluons and of fundamental and anti-fundamental matter states. This suggests the existence of a dual string theory, and a transition to a black hole at high temperature.