Abstract
A search for the rare decays (Bs -> \mu \mu) and (B0 -> \mu\mu) performed in pp collisions at sqrt{s} = 7 TeV is presented. The data sample, collected by the CMS experiment at the LHC, corresponds to an integrated luminosity of 1.14 /fb. In both cases the number of events observed after all selection requirements is consistent with expectations from background and standard model signal predictions. The resulting upper limits on the branching fractions are BF(Bs -> \mu\mu) < 1.9 * 10^{-8} and BF(B0 -> \mu \mu) < 4.6 * 10^{-9} at 95% confidence level (CL). Furthermore, the combination of the results of the search for the decay (Bs -> \mu \mu) by the CMS and LHCb experiments is presented. The combined upper limit is BF < 1.1 * 10^{-8} at 95% CL.
Highlights
IntroductionIn the standard model (SM) of particle physics, flavor changing neutral current decays are highly suppressed (Fig. 1): they are forbidden at tree level and can only proceed through higher-order loop diagrams, they are helicity suppressed by factors of (ml/mB), where ml and mB are the masses of the lepton and B meson and they require an internal quark annihilation within the B meson
The combined upper limit is BF < 1.1 × 10−8 at 95% confidence level (CL)
In the standard model (SM) of particle physics, flavor changing neutral current decays are highly suppressed (Fig. 1): they are forbidden at tree level and can only proceed through higher-order loop diagrams, they are helicity suppressed by factors of2, where ml and mB are the masses of the lepton and B meson and they require an internal quark annihilation within the B meson
Summary
In the standard model (SM) of particle physics, flavor changing neutral current decays are highly suppressed (Fig. 1): they are forbidden at tree level and can only proceed through higher-order loop diagrams, they are helicity suppressed by factors of (ml/mB), where ml and mB are the masses of the lepton and B meson and they require an internal quark annihilation within the B meson. The SM predictions (Tab. 1) are significantly enhanced in several extensions of the SM, in some cases the decay rates are lowered. A (blind) search for the rare decays Bs → μ+μ− and B0 → μ+μ− is presented here, using 1.14 fb−1 of integrated luminosity collected by the CMS experiment in 2011 [1]
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