First Observation of the Decay Bs0K-μ+νμ and a Measurement of |Vub | / |Vcb |

LHCb Collaboration

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The first observation of the suppressed semileptonic Bs0 →K-μ+νμ decay is reported. Using a data sample recorded in pp collisions in 2012 with the LHCb detector, corresponding to an integrated luminosity of 2 fb-1, the branching fraction B(Bs0 →K-μ+νμ ) is measured to be [1.06±0.05(stat)±0.08(syst)]×10-4, where the first uncertainty is statistical and the second one represents the combined systematic uncertainties. The decay Bs0 →Ds-μ+νμ, where Ds- is reconstructed in the final state K+K-π-, is used as a normalization channel to minimize the experimental systematic uncertainty. Theoretical calculations on the form factors of the Bs0K- and Bs0Ds- transitions are employed to determine the ratio of the Cabibbo-Kobayashi-Maskawa matrix elements |Vub|/|Vcb| at low and high Bs0K- momentum transfer.

Original languageEnglish
Article number081804
JournalPhysical Review Letters
Issue number8
Publication statusPublished - 25 Feb 2021

Bibliographical note

Funding Information:
We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies CAPES, CNPq, FAPERJ, and FINEP (Brazil), MOST and NSFC (China), CNRS/IN2P3 (France), BMBF, DFG, and MPG (Germany), INFN (Italy), NWO (Netherlands), MNiSW and NCN (Poland), MEN/IFA (Romania), MSHE (Russia), MICINN (Spain), SNSF and SER (Switzerland), NASU (Ukraine), STFC (United Kingdom), and DOE NP and NSF (US). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland), and OSC (US). We are indebted to the communities behind the multiple open-source software packages on which we depend. Individual groups or members have received support from AvH Foundation (Germany), EPLANET, Marie Skłodowska-Curie Actions, and ERC (European Union), A*MIDEX, ANR, Labex P2IO, and OCEVU, and Région Auvergne-Rhône-Alpes (France), Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for Central Universities, and Sci. and Tech. Program of Guangzhou (China), RFBR, RSF, and Yandex LLC (Russia), GVA, XuntaGal, and GENCAT (Spain), and the Royal Society and the Leverhulme Trust (United Kingdom).

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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