  The mSUGRA 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 LSP. Moreover this strategy will be
applicable for a wider class of bino LSP models, where the lighter stau has a
right component at least of similar size as the left.
