Phase transitions in softly broken N = 2 SQCD at non-zero θ angle Original Research Article

We investigate the behavior of softly broken N = 2 SQCD at non-zero bare theta angle θ0, using superfield spurions to implement the SUSY breaking. We find a first-order phase transition as θ0 is varied from zero to 2π, in agreement with a prediction of ʹt Hooft. The low-energy theta angle θeff, which determines the effective charges of dyonic excitations, has a complicated dependence on θ0 and the breaking parameters.