Anomalies in orbifold field theories

TL;DR

This paper investigates local gauge anomaly constraints in five-dimensional orbifold models with extra dimensions, highlighting the persistence of anomalies at fixed points even when zero modes are removed, affecting model consistency.

Contribution

It demonstrates that gauge anomalies can localize at orbifold fixed points despite zero mode removal, impacting the construction of consistent extra-dimensional theories.

Findings

Anomalies are localized at fixed points in orbifold models.

Naive anomaly cancellation does not ensure gauge invariance.

Implications for supersymmetric models with bulk Higgs fields.

Abstract

We study the constraints on models with extra dimensions arising from local anomaly cancellation. We consider a five-dimensional field theory with a U(1) gauge field and a charged fermion, compactified on the orbifold S^1/(Z_2 x Z_2'). We show that, even if the orbifold projections remove both fermionic zero modes, there are gauge anomalies localized at the fixed points. Anomalies naively cancel after integration over the fifth dimension, but gauge invariance is broken, spoiling the consistency of the theory. We discuss the implications for realistic supersymmetric models with a single Higgs hypermultiplet in the bulk, and possible cancellation mechanisms in non-minimal models.