Light Stops in the MSSM: Implications for Photino Dark Matter and Top Quark Decay

Abstract

We consider the viability of the minimal supersymmetric standard model with a light ($m_{\tilde t_1} < $ 45 GeV) stop. In order for its relic abundance to be cosmologically significant, the photino as dark matter must be quite close in mass to the stop, $(m_{\tilde t_1} - m_{\tilde \gamma}) \simeq 3 - 7 $ GeV. However, as we show, the photino despite its low mass is virtually undetectable by either direct or indirect means. We also discuss the implications of these masses on the top quark branching ratios.