Accurate simulation of the finite density lattice Thirring model

TL;DR

This paper demonstrates that the fermion bag algorithm effectively eliminates the sign problem in simulating the finite density lattice Thirring model, providing accurate benchmarks for future studies.

Contribution

It shows that the fermion bag approach removes the sign problem in certain conditions, offering a more reliable method for simulating similar models.

Findings

Sign problem is eliminated in the massless limit with open boundaries.

Fermion bag method reduces the sign problem with periodic boundaries.

Provides benchmark results for the lattice Thirring model.

Abstract

We present a study of the finite density lattice Thirring model in 1+1 dimensions using the world-line/fermion-bag algorithm. The model has features similar to QCD and provides a test case for exploring the accuracy of various methods of solving sign problems. In the massless limit and with open boundary conditions we show that the sign problem is an artifact of the auxiliary field approach and is completely eliminated in the fermion bag approach. With periodic boundary conditions the sign problem is mild in the fermion bag method. We present accurate results for various quantities in the model that can be used as a benchmark for comparison with other methods of solving sign problems.