Heavy Sneutrinos as Dark Matter

Abstract

We calculate the relic density of very heavy, stable scalar neutrinos in the minimal supersymmetric standard model. We include all two-body final states, as well as the effects of co-annihilation with scalar electrons. We find that the sneutrino relic density is in the cosmologically interesting region $0.1\text{ltwid}{\Omega }_{\text{sn}}{h}^2\text{ltwid}1.0$ for $550\text{gev}\text{ltwid}\text{msn}\text{ltwid}2300\text{gev}$. For nominal values of the parameters of our galactic halo, recent results from the Heidelberg--Moscow direct detection experiment set an upper limit on ${\Omega }_{\text{sn}}$ which is lower by a factor ranging from two to ten, depending on $\text{msn}$.

Comments: 7 pages in LaTeX, plus 1 uuencoded figure (uses epsf), UCSBTH--94--29, UMN--TH--1306/94