Search for Supersymmetry in a Three Lepton Plus Jets Signature

We present a search for three lepton plus jets supersymmetric signal at ATLAS detector, LHC, at sqrt(s)=14 TeV. The signal signature must contain three isolated leptons with pT's above 5 GeV and two jets with pT's above 40 GeV. The leptons must form a same or opposite charge pair. The analysis was done using the Monte Carlo data equivalent to 1 fb-1 of the real data. tt, WZ, Zbb and Z+jets processes were considered as backgrounds. The signal extraction from the backgrounds was done using optimization cuts in five variables: pT's of leptons, HT and missing ET. It was shown that the statistical significance = S/(S+B)=6:3 for 1 fb-1. This allows an early SUSY discovery. The discovery limit = 5 sigma can be reached at 650 pb-1. The effect of the main jet calibration uncertainty determined to be small.