The Strong CP Problem and Discrete Symmetries

TL;DR

This paper proposes a solution to the strong CP problem using spontaneous CP violation and discrete symmetries, predicting an almost right-angled quark unitarity triangle and illustrating the idea with a toy model.

Contribution

It introduces a novel approach combining spontaneous CP violation with discrete symmetries to address the strong CP problem and predicts specific features of the quark mixing matrix.

Findings

Predicts the quark unitarity triangle angle as approximately 90 degrees.

Demonstrates the approach with a toy flavor model.

Shows the viability of the proposed solution.

Abstract

We discuss a possible solution to the strong CP problem which is based on spontaneous CP violation and discrete symmetries. At the same time we predict in a simple way the almost right-angled quark unitarity triangle angle ($\alpha \simeq 90^\circ$) by making the entries of the quark mass matrices either real or imaginary. To prove the viability of our strategy we present a toy flavour model for the quark sector.