Solving the strong CP problem in string-inspired theories with modular invariance

TL;DR

This paper explores how modular invariance solutions to the strong CP problem can be adapted to string-inspired models, considering modular weights, gauge functions, and singularities, affecting string gauge unification.

Contribution

It extends modular invariance solutions to the strong CP problem by incorporating string compactification features like modular weights and gauge kinetic functions.

Findings

Modular invariance solutions can be compatible with string compactification features.

Assumptions about singularities influence string gauge unification.

The approach integrates string-inspired features into CP problem solutions.

Abstract

We show that solutions to the strong CP problem based on modular invariance can be extended to incorporate features that appear in string compactifications: quarks with mostly positive modular weights and non-trivial gauge kinetic functions. This requires assuming that singularities and zeroes only appear at special points, such as decompactification limits. We discuss the impact of these assumptions on string gauge unification.