Phase Transitions in Softly Broken N=2 SQCD at Non-zero Theta Angle

TL;DR

This paper studies phase transitions in softly broken N=2 supersymmetric QCD at non-zero theta angles, revealing a first-order transition and complex dependence of the effective theta angle on parameters.

Contribution

It demonstrates a first-order phase transition at non-zero theta in softly broken N=2 SQCD using superfield spurions, confirming theoretical predictions.

Findings

First-order phase transition as theta varies from 0 to 2π

Complex dependence of effective theta angle on parameters

Agreement with 't Hooft's prediction

Abstract

We investigate the behavior of softly broken $N=2$ SQCD at non-zero bare theta angle $\theta_0$, using superfield spurions to implement the SUSY breaking. We find a first-order phase transition as $\theta_0$ is varied from zero to $2 \pi$, in agreement with a prediction of `t Hooft. The low-energy theta angle $\theta_{eff}$, which determines the effective charges of dyonic excitations, has a complicated dependence on $\theta_0$ and breaking parameters.