Effective Actions Near Singularities: The STU-Model

TL;DR

This paper derives a non-singular, SU(2) invariant low energy effective action for the STU-model near the T=U line, incorporating light W bosons and ensuring consistency with modular invariance and decompactification limits.

Contribution

It introduces a method to 'integrate in' light gauge bosons to resolve singularities in the effective action of the STU-model near symmetry enhancement points.

Findings

Effective action becomes non-singular at T=U

Maintains SU(2) gauge invariance

Consistent with modular invariance and decompactification limit

Abstract

We derive the low energy effective action of the STU-model in four and five dimensions near the line T=U, where SU(2) gauge symmetry enhancement occurs. By `integrating in' the light W^{\pm} bosons together with their superpartners, the quantum corrected effective action becomes non-singular at T=U and manifestly SU(2) invariant. The four-dimensional theory is found to be consistent with modular invariance and the five-dimensional decompactification limit. This talk concisely summarizes results that have been obtained in collaboration with J. Louis and T. Mohaupt.