Study of the rare decays of $$B^0_s$$ and $$B^0$$ into muon pairs from data collected during the LHC Run 1 with the ATLAS detector

Abstract

A study of the decays B0 → µ+µ−and B0s → µ+µ− has been performed using data corresponding to an integrated luminosity of 25 fb−1 of 7 TeV and 8 TeV proton–proton collisions collected with the ATLAS detector during the LHC Run 1. For B0, an upper limit on thebranching fraction is set at B(B0 → µ+µ−) < 4.2 × 10−10 at 95% confidence level. For B0s,the branching fraction B(B0s → µ+µ−) =0.9+1.1−0.8× 10−9 is measured. The results are consistent with the Standard Model expectation with a p-value of 4.8%, corresponding to 2.0 standard deviations.