title: Helical magnetic fields from sphaleron decay and baryogenesis.
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, though the helicity created is smaller than earlier analytical estimates. 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.
authors.affiliation: CERCA, Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7079, USA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Copi
authors.forename: Francesc
authors.initials: F
authors.lastname: Ferrer
authors.forename: Tanmay
authors.initials: T
authors.lastname: Vachaspati
authors.forename: Ana
authors.initials: A
authors.lastname: Achúcarro