Discrete anomalies of binary groups

Abstract

We derive the discrete anomaly conditions for the binary tetrahedral group T′ as well as the binary dihedral groups Q2n. The ambiguities of embedding these finite groups into SU(2) and SU(3) lead to various possible definitions of the discrete indices which enter the anomaly equations. We scrutinize the different choices and show that it is sufficient to consider one particular assignment for the discrete indices. Thus it is straightforward to determine whether or not a given model of flavor is discrete anomaly free.