Rare and semi-rare decays in ATLAS

Recent results in the searches for rare processes involving B-mesons are presented. Particular attention will be given to FCNC processes, such as the decay of Bs and Bd into two muons, and the angular analysis of the decay of Bd -> K* mu mu, where a number of angular coefficients are measured as a function of the invariant mass squared of the di-muon system. Comparison is made to theoretical predictions, including for the observable P’5, for which there has been recent tension between theory and experiment.