Phase structure of strong coupling lattice QCD with overlap fermions at finite temperature and chemical potential

Lattice QCD at finite temperature t and chemical potential mu is studied analytically in the strong coupling limit with overlap fermions. We start from the first order approximately of lattice action with generalized overlap (GO) fermions to derive an effective free energy written in terms of chiral condensate as a function of t and mu with the use of mean field approximation. We elucidate the phase structure on the (mu, T) plane and discover the tricritical point seperating the first and the second order chiral phase transition. Discussion of the doubling problem and higher order terms are given.