The extent of the stop coannihilation strip

Many supersymmetric models such as the constrained minimal supersymmetric extension of the Standard Model (CMSSM) feature a strip in parameter space where the lightest neutralino is identified as the lightest supersymmetric particle, the lighter stop squark is the next-to-lightest supersymmetric particle (NLSP), and the relic cold dark matter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and we explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the may weigh several TeV, and its lifetime may be in the nanosecond range, features that are more general than the specific CMSSM scenarios that we study in this paper.