Rare B Decays: Results and Prospects in ATLAS

Searches of processes beyond the Standard Model (SM) are among the main topics of interest at the ATLAS experiment. Indirect evidence of such processes may be obtained by observing rare leptonic and semi-leptonic decays of hadrons consisting of b quarks. The branching ratio of the decay Bs → µ + µ − is sensitive to theoretical models extending the SM. Its measurement may exclude specific models. The forward-backward asymmetry of the muon pair in semi-muonic decays of Bs , Bd , B+ and Λb hadrons is also sensitive to possible phenomena beyond the SM. The trigger strategy to be used for the study of rare B decays relies on di-muon triggers. Preliminary results regarding the performance of the trigger system are shown. The ATLAS strategy for measuring the branching ratio of Bs → µ + µ − is presented, based on simulated data.