Light Lepton Number Violating Sneutrinos and the Baryon Number of the Universe

TL;DR

This paper explores how light sneutrinos with lepton number violation can coexist with the universe's baryon asymmetry, constraining their properties based on neutrino mass models and electroweak phase transition dynamics.

Contribution

It analyzes the conditions under which light sneutrinos can violate lepton number without erasing the baryon asymmetry, linking neutrino mass models to dark matter hypotheses.

Findings

Sneutrino mass splitting compatible with dark matter only for heavy gauginos.

Lepton number violation constraints depend on electroweak phase transition order.

Baryon asymmetry preservation limits sneutrino properties in supersymmetric models.

Abstract

Recent results of neutrino oscillation experiments point to a nonvanishing neutrino mass. Neutrino mass models favour Majorana-type neutrinos. In such circumstances it is natural that the supersymmetric counterpart of the neutrino, the sneutrino, bears also lepton number violating properties. On the other hand, the fact that the universe exhibits an asymmetry in the baryon and antibaryon numbers poses constraints on the extent of lepton number violation in the light sneutrino sector if the electroweak phase transition is second or weak first order. From the requirement that the Baryon Asymmetry of the Universe should not be washed out by sneutrino induced lepton number violating interactions and sphalerons below the critical temperature of the electroweak phase transition we find that the mass splitting of the light sneutrino mass states is compatible with the sneutrino Cold Dark Matter hypothesis only for heavy gauginos and opposite sign gaugino mass parameters.