Robustness of spontaneous symmetry breaking in a bridge model

TL;DR

This study examines a generalized two-species exclusion model to assess the robustness of spontaneous symmetry breaking, finding that it persists under boundary exchanges and mapping the full phase diagram.

Contribution

It extends the bridge model by including boundary exchanges, demonstrating the robustness of symmetry breaking through analysis and simulations.

Findings

Symmetry breaking persists with boundary exchanges.

Phase diagram delineates symmetric and broken phases.

Mechanism of symmetry breaking remains similar to the original model.

Abstract

A simple two-species asymmetric exclusion model in one dimension with bulk and boundary exchanges of particles is investigated for the existence of spontaneous symmetry breaking. The model is a generalization of the bridge model for which earlier studies have confirmed the existence of symmetry-broken phases, and the motivation here is to check the robustness of the observed symmetry breaking with respect to additional dynamical moves, in particular, the boundary exchange of the two species of particles. Our analysis, based on general considerations, mean-field approximation and numerical simulations, shows that the symmetry breaking in the bridge model is sustained for a range of values of the boundary exchange rate. Moreover, the mechanism through which symmetry is broken is similar to that in the bridge model. Our analysis allows us to plot the complete phase diagram of the model, demarcating regions of symmetric and symmetry-broken phases.