Grassmann Tensor Renormalization Group for two-flavor massive Schwinger model with a theta term

Abstract

We investigate the $N_f=2$ Schwinger model with the massive staggered fermions in the presence of a $2\ddot{I}€$ periodic $\hat{I}¸$ term, using the Grassmann tensor renormalization group. Thanks to the Grassmann tensor network formulation, there is no difficulty in dealing with the massive staggered fermions. We study the $\hat{I}¸$ dependence of the free energy in the thermodynamic limit. Our calculation provides consistent results with the analytical solution in the large mass limit. The results also suggest that the $N_f=2$ Schwinger model on a lattice has a different phase structure from that described by the continuum theory.

9 pages, 4 figures, Contribution to The 41st International Symposium on Lattice Field Theory (LATTICE2024), 28 July - 3 August 2024, Liverpool, UK