Probing dark matter and CMSSM with same-sign dilepton searches at the LHC

We introduce new observables for the study of the inclusive same sign dileptons production at LHC which are built out of ratios of the observed number of same-sign dileptons, both with same $N(\ell,\ell)$ and different flavor $N(\ell,\ell')$. As a case study we apply them to the stau coannihilation region of the constrained minimal supersymmetric standard model. We show that the new variables depend rather mildly on the center of mass energy and how these can be used to constraint the parameter space in the $(m_{1/2},\tanβ)$ plane.