Supersymmetric Dark Matter in the Light of LEP 1.5

Abstract

We discuss the lower limit on the mass of the neutralino $\ddot{I}‡$ that can be obtained by combining data from $e^{+}{e}^{-}$ annihilation at LEP and elsewhere with astrophysical and theoretical considerations. Loopholes in the purely experimental analysis of ALEPH data from the Z peak and LEP 1.5, which appear when $\hat{I}¼<0$ for certain values of the sneutrino mass $m_{\tilde{\hat{I}}½}$ and the ratio $\tan {\hat{I}}^2$ of supersymmetric Higgs vacuum expectation values, may be largely or totally excluded by data from lower-energy $e^{+}{e}^{-}$ data, the hypothesis that most of the cosmological dark matter consists of $\ddot{I}‡$ particles, and the assumption that electroweak symmetry breaking is triggered by radiative corrections due to a heavy top quark. The combination of these inputs imposes $m_χ \ge 21.4~\gev$, if soft supersymmetry-breaking masses are assumed to be universal at the grand-unification scale.

22 pages. one Latex file + nine eps figures