A Quantal Theory of Restoration of Strong CP Symmetry

TL;DR

This paper introduces a mechanism where membrane nucleation in the early universe relaxes the gauge theory CP violating phase in discrete steps, significantly reducing CP violation during cosmological evolution.

Contribution

It presents a novel quantal mechanism involving 4-form flux discharge via membrane nucleation to relax CP violation in gauge theories.

Findings

Membrane nucleation can discretely reduce CP violating phases.

Bubble collisions lead to the melting of CP violation into gauge radiation.

The mechanism operates effectively during early universe radiation domination.

Abstract

We propose a mechanism for relaxing a gauge theory CP violating phase in discrete steps to very small values. The idea is that the CP violating phase includes the magnetic dual of a $4$-form flux which can discharge by the nucleation of membranes. Inside the bubbles surrounded by the membranes, the total CP violating phase is reduced. When the bubbles are produced rapidly during radiation domination in the early universe, near the chiral symmetry breaking scale, they will collide and percolate, melting away into gauge theory radiation and dramatically relaxing CP violation.