Strong constraints on the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-

TL;DR

This paper reports a search for rare Bs and B0 meson decays into muon pairs using LHCb data, setting new upper limits on their branching fractions consistent with Standard Model predictions.

Contribution

First search for Bs and B0 to mu+ mu- decays with 1.0 fb^-1 data, establishing the most stringent upper limits to date.

Findings

Observed events match background expectations

Upper limits on branching fractions are set at 4.5 and 1.0 x 10^-9

Results are consistent with Standard Model predictions

Abstract

A search for Bs -> mu+ mu- and B0 -> mu+ mu- decays is performed using 1.0 fb^-1 of pp collision data collected at \sqrt{s}=7 TeV with the LHCb experiment at the Large Hadron Collider. For both decays the number of observed events is consistent with expectation from background and Standard Model signal predictions. Upper limits on the branching fractions are determined to be BR(Bs -> mu+ mu-) < 4.5 (3.8) x 10^-9 and BR(B0 -> mu+ mu-) < 1.0 (0.81) x 10^-9 at 95% (90%) confidence level.