ATLAS $B_{s} \rightarrow \mu\mu$

A search for Bs → μ + μ − in p p collisions at a centre-of-mass energy of 7 TeV has been performed using data collected with the ATLAS detector in 2011 corresponding to 2.4fb−1 of the integrated luminosity. Bs → μ+μ− is the Flavor Changing Neutral Current process, which is suppressed strongly in the Standard Model (SM), while contributions of unknown particles may enhance its branching ratio (BR). Therefore it is very sensitive channel to prove the physics beyond the SM. The signal region was blinded until the background in signal-free region is well understood. After unblinding, no significant excess was observed in the signal region and the upper limit on the BR was set at 2.2 × 10−8 at 95% C.L.