Helical Magnetic Fields from Sphaleron Decay and Baryogenesis

TL;DR

This paper demonstrates through numerical simulations that baryogenesis processes in the electroweak sector can generate helical cosmic magnetic fields, which may be observable today and serve as probes of fundamental particle physics.

Contribution

It provides the first numerical evidence linking electroweak baryogenesis to the generation of helical magnetic fields in the early universe.

Findings

Electroweak dynamics conserve Chern-Simons number after a transient period.

Baryogenesis can produce magnetic fields of nano-Gauss strength today.

Helical magnetic fields can serve as probes of CP violation in particle physics.

Abstract

Many models of baryogenesis rely on anomalous particle physics processes to give baryon number violation. By numerically evolving the electroweak equations on a lattice, we show that baryogenesis in these models creates helical cosmic magnetic fields. After a transitory period, electroweak dynamics is found to conserve the Chern-Simons number and the total electromagnetic helicity. We argue that baryogenesis could lead to magnetic fields of nano-Gauss strength today on astrophysical length scales. In addition to being astrophysically relevant, such helical magnetic fields can provide an independent probe of baryogenesis and CP violation in particle physics.