Right sneutrino with $\Delta\,L\,=\,2$ masses as non-thermal dark matter

TL;DR

This paper explores a non-thermal dark matter model within the MSSM framework, focusing on right-handed sneutrinos with $ ext{Δ}L=2$ masses, analyzing constraints from cosmological relic densities and particle physics processes.

Contribution

It investigates the viability of right-handed sneutrino dark matter with $ ext{Δ}L=2$ masses, identifying conditions under which such models are consistent with cosmological and particle physics constraints.

Findings

Viable parameter space requires a hierarchy of supersymmetry-breaking masses or strong parameter cancellations.

Constraints from freeze-in relic density and big-bang nucleosynthesis significantly limit scenarios.

Certain $ ext{Δ}L=2$ mass terms are difficult to reconcile with sneutrino dark matter without specific conditions.

Abstract

We consider MSSM with right-chiral neutrino superfields with Majorana masses, where the lightest right-handed sneutrino dominated scalars constitutes non-thermal dark matter (DM). The $\Delta\,L=2$ masses are subject to severe constraints coming from freeze-in relic density of such DM candidates as well as from sterile neutrino $\textit{freeze-in}$. In addition, big-bang Nucleosynthesis and $\textit{freeze-out}$ of the next-to-lightest superparticle shrink the viable parameter space of such a scenario. We examine various $\Delta\,L=2$ mass terms for families other than that $\Delta\,L=2$ masses are difficult to reconcile with a right-sneutrino DM, unless there is either (a) a hierarchy of about 3 orders of magnitudes among various supersymmetry-breaking mass parameters, or, (b) strong cancellation between the higgsino mass and the trilinear supersymmetry breaking mass parameter for sneutrinos.