Gauge Threshold Corrections for Local String Models

TL;DR

This paper investigates gauge threshold corrections in local string models, showing that large bulk volumes influence anomalies and unification scales, with explicit string computations supporting the enhancement from M_s to R M_s.

Contribution

It provides a detailed analysis of gauge threshold corrections in local brane models, highlighting the role of bulk volume and global tadpole cancellation in unification scale predictions.

Findings

Bulk volume significantly affects gauge anomalies and unification scales.

Explicit string computations support the scale enhancement from M_s to R M_s.

Discrepancies are discussed in D3/D7 models compared to effective field theory.

Abstract

We study gauge threshold corrections for local brane models embedded in a large compact space. A large bulk volume gives important contributions to the Konishi and super-Weyl anomalies and the effective field theory analysis implies the unification scale should be enhanced in a model-independent way from M_s to R M_s. For local D3/D3 models this result is supported by the explicit string computations. In this case the scale R M_s comes from the necessity of global cancellation of RR tadpoles sourced by the local model. We also study D3/D7 models and discuss discrepancies with the effective field theory analysis. We comment on phenomenological implications for gauge coupling unification and for the GUT scale.