On the feasibility of a stop NLSP in gravitino dark matter scenarios

Abstract

We analyze the possibility that the lighter stop 1 could be the next-to-lightest supersymmetric particle (NLSP) in models where the gravitino is the lightest supersymmetric particle (LSP). We do not find any possibility for a stop NLSP in the constrained MSSM with universal input soft supersymmetry-breaking masses at the GUT scale (CMSSM), but do find small allowed regions in models with non-universal Higgs masses (NUHM). We discuss the cosmological evolution of stop hadrons. Most 1qq 'sbaryons' and the corresponding 'antisbaryons' annihilate with conventional antibaryons and baryons into 1 'mesinos' and the corresponding 'antimesinos', respectively, shortly after the quark-hadron transition in the early Universe, and most mesinos and antimesinos subsequently annihilate. As a result, insufficient metastable charged stop hadrons survive to alter Big Bang nucleosynthesis. © SISSA 2007.