Phase structure of many flavor lattice QCD at finite temperature

In realistic technicolor models containing many fermions, the electroweak baryogenesis offers a natural scenario for generating baryon number asymmetry. One of the key ingredients is the occurrence of the first order phase transition at finite temperature. As a first step toward the exploration of this possibility on the lattice, we develop an agile method to identify the critical mass for a given Nf, separating the first order and the crossover transition. We explain the outline of our method and demonstrate it by determining the critical mass of Nf-flavors in the presence of light two-flavors. It is found that the critical mass becomes larger with Nf.