Localized tadpoles of anomalous heterotic U(1)'s

TL;DR

This paper studies localized anomalous U(1) gauge symmetries in heterotic string theory on orbifolds, demonstrating consistent anomaly cancellation mechanisms, calculating Fayet-Iliopoulos tadpoles, and analyzing their implications for gauge symmetry breaking.

Contribution

It introduces a unified approach to anomaly cancellation at fixed points in heterotic orbifolds and computes the gauge field profiles and tadpoles explicitly.

Findings

Green-Schwarz mechanism can be applied locally at fixed points

Explicit shape of Fayet-Iliopoulos tadpoles derived

Gauge field backgrounds influence symmetry breaking patterns

Abstract

We investigate the properties of localized anomalous U(1)'s in heterotic string theory on the orbifold T^6/Z_3. We argue that the local four dimensional and original ten dimensional Green-Schwarz mechanisms can be implemented simultaneously, making the theory manifestly gauge invariant everywhere, in the bulk and at the fixed points. We compute the shape of the Fayet-Iliopoulos tadpoles, and cross check this derivation for the four dimensional auxiliary fields by a direct calculation of the tadpoles of the internal gauge fields. Finally we study some resulting consequences for spontaneous symmetry breaking, and derive the profile of the internal gauge field background over the orbifold.