First-principle simulations of 1+1d quantum field theories at $\theta=\pi$ and spin-chains

TL;DR

This paper introduces a novel lattice simulation method that overcomes the sign problem in 2-flavor U(1) gauge-Higgs models at θ=π, demonstrating their equivalence to spin-chain universality classes.

Contribution

The authors develop a new discretization and dualization approach enabling sign-problem-free simulations of topological U(1) gauge theories at θ=π.

Findings

Model is in the spin-chain universality class

First ab initio demonstration of this equivalence

New approach effectively handles sign-problem in gauge theories

Abstract

We present a lattice study of a 2-flavor $U(1)$ gauge-Higgs model quantum field theory with a topological term at $\theta=\pi$. Such studies are prohibitively costly in the standard lattice formulation due to the sign-problem. Using a novel discretization of the model, along with an exact lattice dualization, we overcome the sign-problem and reliably simulate such systems. Our work provides the first ab initio demonstration that the model is in the spin-chain universality class, and demonstrates the power of the new approach to $U(1)$ gauge theories.