Search for the rare decays Bs,d->mumu at LHCb

TL;DR

This paper reports on a search for rare Bs and Bd meson decays into muon pairs using LHCb data, setting upper limits on their branching ratios and combining results from multiple datasets.

Contribution

The study provides the first upper limits on Bs and Bd to mu mu decay branching ratios at LHCb, improving constraints on new physics models.

Findings

Upper limit for BR(Bs->mumu) < 1.3 x 10^{-8} at 90% CL

Upper limit for BR(Bd->mumu) < 4.2 x 10^{-9} at 90% CL

Combined dataset results in BR(Bs->mumu) < 1.2 x 10^{-8} at 90% CL

Abstract

A search for the Bs->mumu and Bd->mumu decays is presented using ~300 pb-1 of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The measured upper limit for the branching ratio of the Bs->mumu decay is BR(Bsmumu) < 1.3 (1.6) x 10^{-8} at 90% (95%) confidence level (CL), while in the case of the Bd->mumu decay the measured upper limit is BR(Bdmumu) < 4.2 (5.1) x 10^{-9} at 90% (95%) CL. A combination with the 2010 dataset results in BR(Bsmumu) < 1.2 (1.5) x 10^{-8} at 90% (95%) CL.