Functional Integrals and Convergence of Partition Function in Sine–Gordon–Thirring Model

Abstract

The effective action in 1D sine-Gordon-Thirring model with impurities coupling is derived by means of functional integral method. For strong coupling model, the convergence of partition function is proved when coupling constants and wave vector satisfy certain constraint conditions. The fermion condense density in stable phase structure is obtained from the extremum of two-order effective action. The results showed that the non-perturbation method of functional integrals can be applied to study strong coupling rang of fermion system.