Detection of SUSY Signals in Stau Neutralino Co-annihilation Region at the LHC

Abstract

We study the prospects of detecting the signal in the stau neutralino (τ̃1−χ̃10) co‐annihilation region at the LHC using tau (τ) leptons. The co‐annihilation signal is characterized by the τ̃1 and χ̃10 mass difference (ΔM) to be 5–15 GeV to be consistent with the WMAP measurement of the cold dark matter relic density as well as all other experimental bounds within the minimal supergravity model. Focusing on τ’s from χ̃20 → ττ̃ → ττχ̃10 decays in g̃ and q̃ production, we consider inclusive E/T+jet+3 τ production, with two τ’s above a high ET threshold and a third τ above a lower threshold. Two observables, the number of opposite‐signed τ pairs minus the number of like‐signed τ pairs and the peak position of the di‐tau invariant mass distribution, allow for the simultaneous determination of ΔM and Mg̃. For ΔM = 9 GeV and Mg̃ = 850 GeV with 30 fb−1 of data, we can measure ΔM to 15% and Mg̃ to 6%.