Slepton Discovery in Electroweak Cascade Decay

Abstract

The LHC studies on the MSSM slepton sector have mostly been focused on direct slepton Drell-Yan pair production. In this paper, we analyze the case when the sleptons are lighter than heavy neutralinos and can appear in the on-shell decay of neutralino states. In particular, we have studied the χ_1^\pm χ_2^0 associated production, with the consequent decays of χ_1^\pm and χ_2^0 via on-shell sleptons. The invariant mass of the lepton pairs, m_{\ell\ell}, from the neutralino decay has a distinctive triangle shape with a sharp kinematic cutoff. We discuss the utilization of this triangle shape in m_{\ell\ell} distribution to identify the slepton signal. We studied the trilepton plus missing E_T signal and obtained the effective cross section, σ\times BR \times acceptance, that is needed for a 5σdiscovery as a function of the cutoff mass for the LHC with center of mass energy 14 TeV and 100 fb^{-1} integrated luminosity. Our results are model independent such that they could be applied to other models with similar decay topology. When applied to the MSSM under simple assumptions, it is found that with 100 fb^{-1} integrated luminosity, a discovery reach in the left-handed slepton mass of about 600 GeV could be reached, which extends far beyond the slepton mass reach in the usual Drell-Yan studies.

20 pages, 5 figures