How to Reach the Correct sin^2\theta_W and \alpha_S in String Theory

TL;DR

This paper explores how specific heterotic string compactifications can reconcile the predicted weak mixing angle and strong coupling constant with observed values without introducing problematic intermediate scales.

Contribution

It demonstrates a method within (0,2) heterotic superstring compactifications to achieve correct low-energy coupling constants through moduli-dependent threshold corrections.

Findings

Successful adjustment of threshold corrections to match experimental values

Avoidance of small intermediate scales in string compactifications

Potential framework for realistic string phenomenology

Abstract

Effective theories with the matter content of the minimal supersymmetric Standard Model below the string scale M_string predict a wrong value for the weak--mixing angle sin^2\theta_W and strong coupling constant \alpha_S at the scale M_Z. To resolve this problem one needs large threshold corrections. At the same time one would like to avoid introducing new intermediate scales that are small compared to M_string. Two requests which seem to be incompatible. We show how both requirements can be satisfied in a class of (0,2) heterotic superstring compactifications with a natural choice of the vevs of the moduli fields entering the moduli dependent string threshold corrections.