LHCb: Search for the rare decays $B^0_{(s)} \to \mu^+\mu^-$ with the LHCb Experiment

A review of the search for the very rare decays $B^{0}_{s} \rightarrow \mu^+ \mu^-$ and $B^{0} \rightarrow \mu^+ \mu^-$ with the LHCb experiment is presented. These decays are suppressed within the Standard Model as they can only occur via helicity suppressed loop diagrams. However, their amplitudes can be significantly different in many New Physics scenarios, especially in those with an extended Higgs sector. Therefore, these decays are a sensitive probe of physics beyond the Standard Model. The study is performed using $\sim 37$ $pb^{-1}$ of pp collisions at $\sqrt{s}$ = 7 TeV collected by the experiment at the Large Hadron Collider at CERN. For these dimuon decays the LHCb has reached sensitivities similar to the best existing limits. The resulting upper limits are $\mathcal{B}(B^{0}_{s} \rightarrow \mu^+ \mu^-)<$ 56 $\times$ $10^{-9}$ and $\mathcal{B}(B^{0} \rightarrow \mu^+ \mu^-)<$ 15 $\times$ $10^{-9}$ at $95\%$ confidence level. With the number of pp colisions expected in 2011 the LHCb will be able to explore the region of branching ratios $\sim 10^{-8}$.