SUSY signatures at LHC

SUSY is perhaps the most promising candidate for physics beyond the Standard Model; it also provides a good test of detector performance. The ATLAS [1] and CMS [2] Collaborations at the CERN Large Hadron Collider (LHC) have therefore devoted a lot of effort to studying SUSY signatures and measurements. This talk provides an overview of that work with emphasis on new results since the overviews in Ref. 3 and 4. The SUSY cross section at the LHC is dominated by the associated strong production of gluinos and squarks. If R parity is conserved, these decay into the lightest SUSY particle χ1, which escapes the detector, plus quarks, gluons, and perhaps other Standard Model particles. Thus, SUSY provides signatures containing at least jets and large missing transverse energy / ET . The LHC should be able to observe these signals for g and q masses up to about 2TeV with only 10 fb−1 of integrated luminosity. The challenge at the LHC is not to discover TeV-scale SUSY (assuming it exists) but to make precision measurements of masses and other quantities. Since the decay products of each SUSY particle contain an invisible χ1, no mass peaks can be reconstructed directly. Instead, masses must be inferred [5] from kinematic endpoints and other properties of the events. Developing methods to do this has been a main emphasis of the studies to date. Typically, events are simulated for a particular SUSY model and for the Standard Model backgrounds using a parton shower Monte Carlo program such as HERWIG [6], ISAJET [7], or PYTHIA [8], the detector response is simulated using a fast parameterization, cuts are made to give a good signal/background, and various kinematic distributions are reconstructed. A number of examples are presented below.