Dynamical Gauge Coupling Constants

TL;DR

This paper reviews how string theory determines gauge coupling constants through moduli fields, discussing their connection to low-energy physics, supersymmetry breaking, and string unification prospects.

Contribution

It provides a comprehensive review of approaches to relate string theory moduli-dependent couplings to realistic low-energy gauge constants, including threshold effects and unification scenarios.

Findings

Gauge couplings are dynamically set by moduli vacuum expectation values.

Supersymmetry breaking impacts the determination of gauge constants.

String threshold corrections influence unification prospects.

Abstract

In string theory the coupling parameters are functions of moduli fields. The actual values of the coupling constants are then dynamically determined through the vacuum expextation values of these fields. We review the attempts to connect such theories to low energy effective field theories with realistic gauge coupling constants. This includes a discussion of supersymmetry breakdown, the question of a running dilaton, string threshold calculations and the possibility of string unification.