Freeze-out of baryon number in low-scale leptogenesis

Abstract

Low-scale leptogenesis provides an economic and testable description of the origin of the baryon asymmetry of the Universe. In this scenario, the baryon asymmetry of the Universe is reprocessed from the lepton asymmetry by electroweak sphaleron processes. Provided that sphalerons are fast enough to maintain equilibrium, the values of the baryon and lepton asymmetries are related to each other. Usually, this relation is used to find the value of the baryon asymmetry at the time of the sphaleron freeze-out. To put in other words, the formula which is valid only when the sphalerons are fast, is applied at the moment when they are actually switched off. In this paper, we examine the validity of such a treatment. To this end, we solve the full system of kinetic equations for low-scale leptogenesis. This system includes equations describing the production of the lepton asymmetry in oscillations of right-handed neutrinos, as well as a separate kinetic equation for the baryon asymmetry. We show that for some values of the model parameters, the corrections to the standard approach are sizeable. We also present a feasible improvement to the ordinary procedure, which accounts for these corrections.

arXiv comment17 pages, 6 figures

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• GeV-scale hot sterile neutrino oscillations: a numerical solution
• Precision study of GeV-scale resonant leptogenesis
• Parameter space of baryogenesis in the $\nu$MSM
• Bounds on right-handed neutrino parameters from observable leptogenesis
• Relativistic and spectator effects in leptogenesis with heavy sterile neutrinos
• Kinetic equations for sterile neutrinos from thermal fluctuations
• Baryogenesis and Dark Matter from Freeze-In
• Freeze-in and freeze-out generation of lepton asymmetries after baryogenesis in the $\nu$MSM
• Confronting the low-scale seesaw and leptogenesis with neutrinoless double beta decay
• Robustness of ARS Leptogenesis in Scalar Extensions
• Sterile neutrino rates for general $M$, $T$, $\mu$, $k$: review of a theoretical framework
• Reconciling resonant leptogenesis and baryogenesis via neutrino oscillations
• Freeze-in Leptogenesis via Dark-Matter Oscillations