Active-sterile neutrino oscillations in the early Universe with full collision terms

Abstract

Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli blocking. Finally, we devise a new approximation scheme, which improves upon some of the shortcomings of previous schemes.

30 pages, 7 figures

References in corpus (7)

• Big-Bang Nucleosynthesis
• Full Boltzmann equations for leptogenesis including scattering
• Sterile neutrinos, lepton asymmetries, primordial elements: how much of each?
• Collisional production of sterile neutrinos via secret interactions and cosmological implications
• Multi-momentum and multi-flavour active-sterile neutrino oscillations in the early universe: role of neutrino asymmetries and effects on nucleosynthesis
• Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis
• Neutrino constraints: what large-scale structure and CMB data are telling us?

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