Neutrino Spin Flavor Precession and Leptogenesis

TL;DR

This paper explores how primordial magnetic fields could induce neutrino spin flavor precession, significantly affecting leptogenesis and the resulting baryon asymmetry of the universe.

Contribution

It introduces the impact of primordial magnetic fields on neutrino spin flavor precession and its influence on leptogenesis, a novel aspect not previously considered.

Findings

Lepton asymmetry may be reduced by 50% due to spin flavor precession.

Leptogenesis dynamics differ from the standard scenario, with continued oscillations after the electroweak phase transition.

Primordial magnetic fields at the electroweak scale can be strong enough to influence leptogenesis.

Abstract

We argue that \Delta L=2 neutrino spin flavor precession, induced by the primordial magnetic fields, could have a significant impact on the leptogenesis process that accounts for the baryon asymmetry of the universe. Although the extra galactic magnetic fields is extremely weak at present time (about 10^{-9} Gauss), the primordial magnetic filed at the electroweak scale could be quite strong (of order 10^{17} Gauss). Therefore, at this scale, the effects of the spin flavor precession are not negligible. We show that the lepton asymmetry may be reduced by 50% due to the spin flavor precession. In addition, the leptogenesis will have different feature from the standard scenario of leptogenesis, where the lepton asymmetry continues to oscillate even after the electroweak phase transition.