MT2 as a variable for discovering supersymmetry

Abstract

We investigate the feasibility of discovering supersymmetry at the Large Hadron Collider (LHC) from the pair production of the second lightest neutralinos or the lightest charginos, where each decays to jet pairs, via a W or Z boson, and to the lightest neutralino. The study is performed within the framework of the Constrained Minimal Supersymmetric Standard Model, at a parameter point with high sfermion masses. Data samples at an integrated luminosity of 4.73 fb^-1 are obtained with Monte Carlo simulated proton-proton collisions at a center of mass energy of 7 TeV. The kinematic variable stransverse mass, MT2, is used to try to separate the signal from the Standard Model background. This variable is an extension of transverse mass for events resulting in two invisible particles. The Bi-Event Subtraction Technique is used to separate the true W and Z bosons from combinatoric background. We find a tiny excess of fractional events for large values of MT2, in a region completely free of any background. The excess is too small to be detectable at the LHC at a luminosity of 4.73 fb^-1. We also find that The Bi-Event Subtraction Technique slightly diminishes the potential of MT2 to separate signal from background.