Application of Non-Perturbative Renormalization Group to Nambu-Jona-Lasinio/Gross-Neveu model at Finite Temperature and Chemical Potential

Abstract

The chiral phase structure of the Nambu-Jona-Lasinio/Gross-Neveu model at finite temperature T and finite chemical potential μis investigated using (Wilsonian) Non-Perturbative Renormalization Group (NPRG). In the large N_c limit, the solutions of NPRG with various cutoff schemes are shown. For a sufficiently large ultra-violet cutoff, NPRG results coincide with those of Schwinger-Dyson equation and have little cutoff scheme dependence. Next, to improve the approximation, we incorporate the mesonic fluctuations. We introduce the auxiliary fields for mesons, and then derive NPRG equation for finite N_c. The chiral phase structure on (T,μ) plane beyond the leading of 1/N_c expansion is investigated in the sharp cutoff limit. N_c dependence of chiral phase diagram is obtained.

21 pages, 10 epsf figures, to be published in Progress of Theoretical Physics