Density Induced Phase Transitions in the Schwinger Model: A Study with Matrix Product States

TL;DR

This paper uses matrix product states to numerically analyze phase transitions in the multiflavor Schwinger model at nonzero chemical potential, successfully locating phase boundaries and demonstrating tensor networks' effectiveness in overcoming the sign problem.

Contribution

It extends previous analytical results to the massive case and showcases tensor networks as a powerful tool for lattice gauge theory calculations.

Findings

Reproduced analytical phase structure for massless two-flavor case

Extended analysis to massive case without analytical predictions

Precisely located phase transitions in the mass-chemical potential plane

Abstract

We numerically study the zero temperature phase structure of the multiflavor Schwinger model at nonzero chemical potential. Using matrix product states, we reproduce analytical results for the phase structure for two flavors in the massless case and extend the computation to the massive case, where no analytical predictions are available. Our calculations allow us to locate phase transitions in the mass-chemical potential plane with great precision and provide a concrete example of tensor networks overcoming the sign problem in a lattice gauge theory calculation.