Monopole Catalyzed Baryogenesis with a $\theta$ angle

TL;DR

This paper demonstrates that monopoles in GUTs can catalyze baryogenesis at GeV temperatures via a CP-violating $ heta$-term, producing the observed baryon asymmetry without conflicting with current experimental bounds.

Contribution

It is the first to show monopole catalyzed baryogenesis at low temperatures using a $ heta$-term in the minimal SU(5) GUT model, with potential detectability in future experiments.

Findings

Monopoles can generate the baryon asymmetry at GeV scales.

The required monopole abundance is below current experimental limits.

Baryogenesis occurs even with a $ heta$ below neutron EDM bounds.

Abstract

Monopoles are generally expected in Grand Unified Theories (GUTs) where they can catalyze baryon decay at an unsuppressed rate by the Callan-Rubakov effect. For the first time, we show this catalysis effect can generate the observed baryon asymmetry at GeV scale temperatures. We study the minimal SU(5) GUT model and demonstrate that monopoles-fermion scattering with a $CP$-violating $\theta$-term leads to realistic baryogenesis even when $\theta\lesssim 10^{-10}$ is below the neutron EDM bound, potentially detectable in the future measurements. Our calculation also shows that to generate the observed baryon asymmetry, the abundance of the monopoles is below the current experiential bounds.