Using tau polarization to probe the stau co-annihilation region of the minimal supergravity model at the LHC

Abstract

The minimal supergravity model predicts the polarization of the tau coming from the stau to bino decay in the co-annihilation region to be $+1$. This can be exploited to extract this soft tau signal at LHC and also to measure the tiny mass differences between the stau and the bino lightest superparticle. Moreover, this strategy will be applicable for a wider class of bino lightest superparticle models, where the lighter stau has a right component at least of similar size as the left.