On the Convergence of the Expansion of Renormalization Group Flow Equation

Abstract

We compare and discuss the dependence of a polynomial truncation of the effective potential used to solve exact renormalization group flow equation for a model with fermionic interaction (linear sigma model) with a grid solution. The sensitivity of the results on the underlying cutoff function is discussed. We explore the validity of the expansion method for second and first-order phase transitions.

Comments: 12 pages with 10 EPS figures included; revised version