Observational manifestations of anomaly inflow

TL;DR

This paper explores how anomaly inflow in theories with extra dimensions can lead to observable modifications in electromagnetic fields, providing potential low-energy signatures of extra dimensions and implications for anomaly cancellation.

Contribution

It analyzes the physical consequences of gauge anomaly non-cancellation in 4D effective theories derived from higher-dimensional models, highlighting observable electromagnetic effects.

Findings

Parallel electric and magnetic fields are modified in the presence of anomaly inflow.

Such modifications occur for particles with electric charge and magnetic moment.

Absence or smallness of effects constrains theories with extra dimensions.

Abstract

In theories with chiral couplings, one of the important consistency requirements is that of the cancellation of a gauge anomaly. In particular, this is one of the conditions imposed on the hypercharges in the Standard Model. However, anomaly cancellation condition of the Standard Model looks unnatural from the perspective of a theory with extra dimensions. Indeed, if our world were embedded into an odd-dimensional space, then the full theory would be automatically anomaly free. In this paper we discuss the physical consequences of anomaly non-cancellation for effective 4-dimensional field theory. We demonstrate that in such a theory parallel electric and magnetic fields get modified. In particular, this happens for any particle possessing both electric charge and magnetic moment. This effect, if observed, can serve as a low energy signature of extra dimensions. On the other hand, if such an effect is absent or is very small, then from the point of view of any theory with extra dimensions it is just another fine-tuning and should acquire theoretical explanation.