One loop corrections to coupling constants in String Effective Field Theory

TL;DR

This paper calculates one-loop corrections to gauge couplings, moduli metrics, and Yukawa couplings in a string effective field theory using a novel amplitude regularization method.

Contribution

It introduces a new method for computing exact string amplitudes and applies it to derive one-loop corrections in a specific orbifold model.

Findings

One-loop gauge coupling corrections derived from D-field correlator.

Moduli Kähler metric renormalization at one loop.

Yukawa coupling corrections from uncharged F-field correlator.

Abstract

In the framework of a recently proposed method for computing exactly string amplitudes regularized in the infra-red, I determine the one-loop correlators for auxiliary fields in the symmetric $Z_2\times Z_2$ orbifold model. The $D$-field correlation function turns out to give the one-loop corrections for the gauge couplings, which amounts to a string-theory supersymmetry Ward identity. The two-point function for uncharged $F$ fields leads to the one-loop renormalization of the moduli K\"ahler metric, and eventually to the corrections for the Yukawa couplings.