Search for the Rare Decays B0s → μ+ μ− and B0 → μ+ μ−

A search for the decays Bs0→μ+μ- and B 0→μ +μ - is performed with 0.37 fb -1 of pp collisions at s=7 TeV collected by the LHCb experiment in 2011. The upper limits on the branching fractions are B(Bs0→μ+μ-)<1.6×10-8 and B(B0→μ+μ-)<3.6×10-9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to B(Bs0→μ+μ-)<1.4×10-8 and B(B0→μ+μ-)<3.2×10-9 at 95% confidence level. © 2012 CERN.