SPS5 SUSY search at ATLAS

The achievable precision of kinematic endpoint and SUSY mass measurements at the ATLAS detector was estimated for mSUGRA point SPS5. This point is characterized by the light stop squark with mass 236 GeV. Although stop pair production represents 49% of the total SUSY production, stop pair signal can not be isolated at SPS5 because on the average at least one of the two final state b jets has transverse momentum below the detection threshold. From the analysis of the left squark cascade decay five kinematic endpoints were reconstructed in order to extract masses of the SUSY particles involved in the decay. Masses of the left squark, right slepton and two lightest neutralinos were reconstructed with the precision of 9%, 17%, 29% and 15% respectively. Gluino decay to light stop squark with hadronic final state was analysed and the kinematic endpoint of the top-bottom invariant mass was reconstructed at the position consistent with theoretically predicted value.