Search and measurement of the B → μμ rare processes with LHC Run I data

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• 作者：Nuno T. Leonardo ; on behalf of the CMS Collaboration
• 关键词：LHC ; CMS ; rare decays ; heavy flavor ; B physics ; FCNC ; searches for physics beyond the standard model
• 刊名：Nuclear and Particle Physics Proceedings
• 出版年：2016
• 出版时间：April-June 2016
• 年：2016
• 卷：273-275
• 期：Complete
• 页码：1308-1313
• 全文大小：526 K

文摘

The decays ${\text{B}}_s^0\to {\mu }^{+}{\mu }^{-}$ and B⁰→μ⁺μ⁻${\text{B}}^0\to {\mu }^{+}{\mu }^{-}$ are highly suppressed in the standard model constituting sensitive probes of new physics. We present the results of a search for these rare decays in proton-proton collisions using the full data sample collected by the CMS experiment during LHC Run I. Through a fit to the dimuon invariant-mass spectrum, an excess of events with respect to the background is observed, compatible with the ${\text{B}}_s^0({\text{B}}^0)$ signal with a significance of 4.3 (2.0) standard deviations (σ  ). The measured branching fractions are $\mathcal{B}({\text{B}}_s^0\to {\mu }^{+}{\mu }^{-})=({3.0}_{-0.9}^{+1.0})\times {10}^{-9}$ and $\mathcal{B}({\text{B}}^0\to {\mu }^{+}{\mu }^{-})=({3.5}_{-1.8}^{+2.1})\times {10}^{-10}$. The combination of the CMS and LHCb results, using their full Run I data samples, yield an event excess compatible with the ${\text{B}}_s^0(B^0)$ signal with a significance in excess of 6σ(3σ)$6\sigma (3\sigma )$. The ongoing and projected accelerator and detector upgrades will allow to establish and to carry out precision measurements of both rare decays, and explore novel observables with further sensitivity to new physics effects.