In order that discrete symmetries should not be violated by gravitational effects, it is necessary to gauge them. In this paper we discuss the gauging of ZZN from the breaking of a high energy SU(N) gauge symmetry, and derive consistency conditions for the resulting discrete symmetry from the requirement of anomaly cancellation in the parent symmetry. These results are then applied to a detaile...

We study 't Hooft anomalies for a global discrete internal symmetry G. We construct examples of bosonic field theories in three dimensions with a nonvanishing 't Hooft anomaly for a discrete global symmetry. We also construct field theories in three dimensions with a global discrete internal symmetry G(1) × G(2) such that gauging G(1) necessarily breaks G(2) and vice versa. This is analogous to...

Krauss and Wilczek have shown that an unbroken discrete gauge symmetry is respected by gravitationally mediated processes. This has led to a search for such a symmetry compatible with the standard model or MSSM that would protect protons from gravitationally mediated decay in a universe with a low scale for quantum gravity (large extra dimensions). The fact that the discrete symmetry must remai...

We examine an interesting scenario to solve the domain wall problem recently suggested by Preskill, Trivedi, Wilczek and Wise. The effective potential is calculated in the presence of the QCD axial anomaly. It is shown that some discrete symmetries such as CP and Z2can be anomalous due to a so-called K-term induced by instantons. We point out that Z2domain-wall problem in the two-doublet standa...