LHC Program for Very Rare B-Decays

This talk reviews ATLAS, CMS and LHCb potential in measurement of dimuonic rare B-decays B_s->mu+mu- and B0->mu+mu-. Branching ratios of these decays are small due to helicity suppression and Flavour Chaning Neutral Currents forbidden at tree level. Accounting clear theoretical picture for the branching ratios prediction and simple experimental signature, measurement of the rates provides excelent probe of New Physics effects. While present experimental upper limits from Tevatron are roughly 50x above Standard Model prediction, LHC experiments will reach the Standard model branchings already around the end of initial low-luminosity stage of LHC (30 fb^-1). In this talk, offline analysis and the expected number of signal and background events are presented. Because of very small branchings, background coming from misidentifications effects and rare exclusive and exotic decays can play an importan role. Therefore part of this talk is also devoted to study of these background sources.