Search for the Associated Production of Charginos and Neutralinos in Proton-Antiproton Collisions at √s = 1.96 TeV with the DØ Detector at the Tevatron

Abstract

A search for Supersymmetry is performed via the associated production of charginos and neutralinos in final states consisting of three charged leptons and missing transverse energy using data collected with the \Dzero\ detector at a center-of-mass energy of 1.96~TeV at the Fermilab Tevatron Collider. The data sample corresponds to an integrated luminosity of $\sim$ 2.3 fb$^{-1}$. This final state is considered one of the most promising channels in the search for supersymmetric particles because of its low Standard Model background. A dedicated event selection is developed and events with two muons plus an additional isolated track or events with two electrons plus an additional isolated track are analyzed. The requirement of an isolated track replaces the third charged lepton in the event. After all selection cuts are applied, in total 7 events are selected in the data with an expected number of background events of 5.24$\pm$0.40~(stat)$\pm$0.30~(syst). Due to the good agreement of events observed in data with the expectation of the Standard Model backgrounds, no evidence for Supersymmetry is found. The present analyses are considered in combination with three other decay channels and limits on the production cross section times leptonic branching fraction are set. The results are interpreted in a constrained scenario and exclusion regions are derived as a function of $m_0$ and $m_{1/2}$.