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\ltwid\Omega_{\sn}h^2\ltwid 1.0 for 550\gev\ltwid\msn\ltwid 2300\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_{\sn} which is lower by a factor ranging from two to ten, depending on \msn.Comment: 7 pages in LaTeX, plus 1 uuencoded figure (uses epsf), UCSBTH--94--29, UMN--TH--1306/9