LHC program for very rare B decays

Abstract

This paper gives an overview of ATLAS, CMS and LHCb potential in measurement of di-muonic rare B-decays B s 0 → μ + μ − and B d 0 → μ + μ − . Branching ratios (BR) of these decays are small due to helicity suppression and Flavour Changing Neutral Currents (FCNC) forbidden at tree level. Accounting clear theoretical picture for the BR prediction and simple experimental signature, measurement of the BR provides excellent probe of New Physics effects. While present experimental upper limits from Tevatron are roughly 50× above Standard Model (SM) prediction, LHC experiments will reach the SM branching already around the end of initial low-luminosity stage of LHC ( 30 fb −1 ) . In the paper, offline analysis and the expected number of signal and background events are presented. Because of small BR, background coming from misidentification effects and rare exclusive and exotic decays can be important. Therefore part of this paper is also devoted to study of these background sources.