Search for Supersymmetry and kinematic endpoint measurement in final states with two tau leptons with the ATLAS detector at the LHC

Discovery prospects for Supersymmetry in final states with at least two tau leptons and large missing transverse energy are evaluated for LHC proton-proton collisions measured with the ATLAS detector. In a first study based on Monte Carlo simulation, a Supersymmetry signal selection is developed for fully hadronic, semileptonic and fully leptonic di-tau decays in events produced in proton-proton collisions with a center-of-mass energy of √s=10 TeV. The prospects of measuring the kinematic endpoint of the di-tau invariant mass distribution assuming an integrated luminosity of ∫ L dt=1 fb−1 are evaluated for different mSUGRA scenarios along with the discovery reach. In a second study, a search for Supersymmetry in the fully hadronic channel is performed, using ∫ L dt=35 pb−1 of ATLAS data collected with proton-proton collisions at √s=7 TeV between June 24th and October 29th 2010. Two events are observed, which is consistent with the Standard Model background expectation of NSM = 0.77 ± 0.19(stat) -0.33+0.55 (syst). Interpreted in mSUGRA, limits on m0 and m1/2 are set for tan ß=40, a positive higgsino mixing parameter and A0 =0 GeV or A0 =-500 GeV. These limits constitute the first results of SUSY searches with tau leptons within the ATLAS experiment.