Studies of a low mass SUSY model at ATLAS with full simulation

SU4 low mass SUSY model was studied at ATLAS with fill Geant4 simulation. With a production cross section of 270 pb and masses in the range 60 - 450 GeV, SU4 seems to be a promising target for SUSY searches with early ATLAS data. Multijet events with a missing energy and b jets were analysed for the inclusive searches and the light stop search from the gluino decay to stop and top where the final state top - bottom invariant mass distribution was reconstructed with a kinematic endpoint close to the expected position. Pure hadronic events with the missing energy and no b jets were analysed for the right squark search from the right squark pair events where the distribution of Cambridge m$_{T2}$ variable was reconstructed with a kinematic endpoint consistent to the SU4 right squark mass value. With only 200 pb$^{-1}$ of data, Standard Model backgrounds can be suppressed to the S/B level of about 3 in the inclusive searches, higher than 4 in the light stop search and above 1 in the right squark search.