Localized nonabelian anomalies at orbifold fixed points

TL;DR

This paper investigates localized nonabelian anomalies at orbifold fixed points in heterotic string compactifications, demonstrating their cancellation via a Green-Schwarz mechanism variant, ensuring consistency of the effective theory.

Contribution

It introduces a method to cancel fixed point anomalies in orbifold compactifications using a modified Green-Schwarz mechanism, extending anomaly cancellation techniques.

Findings

Localized fixed point anomalies are present in heterotic orbifold models.

A variant of the Green-Schwarz mechanism cancels these anomalies.

The effective 4D theory remains consistent despite localized anomalies.

Abstract

Orbifold compactifications of 10D heterotic strings do allow different sets of chiral fermions at different fixed points. Even if the effective 4D theory is anomaly free by including the bulk fermions, there arise abelian and nonabelian fixed point anomalies from these chiral fermions. As the underlying string theory is well defined these localized fixed point anomalies of the chiral fermions are to be cancelled by a variant of the Green-Schwarz mechanism.