A CPT anomaly

TL;DR

This paper investigates a CPT anomaly in chiral gauge theories on specific spacetime manifolds, revealing a CPT-odd term in the effective action due to quantum effects, with potential implications for particle physics and cosmology.

Contribution

It demonstrates the existence of a CPT anomaly in chiral gauge theories on manifolds with compact dimensions, highlighting the role of infrared and ultraviolet effects in generating CPT-odd terms.

Findings

CPT-odd term appears in the effective gauge action

Anomaly depends on the topology of spacetime

Potential relevance to elementary particle physics and cosmology

Abstract

We consider chiral gauge theories defined over a four-dimensional spacetime manifold with a Cartesian product structure for at least one compact spatial dimension. For a simple setup, we calculate the effective gauge field action by integrating out the chiral fermions, while maintaining gauge invariance. Due to a combination of infrared and ultraviolet effects, there appears a CPT-odd term in the effective gauge field action. This CPT anomaly could occur in chiral gauge theories relevant to elementary particle physics, provided the spacetime manifold has the appropriate topology. Two possible applications for cosmology are discussed.