First measurement of the CP -violating phase in Bs0→J/ψ(→ e+e-) ϕ decays

LHCb Collaboration

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A flavour-tagged time-dependent angular analysis of Bs0→J/ψϕ decays is presented where the J/ ψ meson is reconstructed through its decay to an e+e- pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 \,Te V , corresponding to an integrated luminosity of 3 \,fb-1. The CP-violating phase and lifetime parameters of the Bs0 system are measured to be ϕs= 0.00 ± 0.28 ± 0.07 \,rad , Δ Γs= 0.115 ± 0.045 ± 0.011 \,ps-1 and Γs= 0.608 ± 0.018 ± 0.012 \,ps-1 where the first uncertainty is statistical and the second systematic. This is the first time that CP-violating parameters are measured in the Bs0→J/ψϕ decay with an e+e- pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions.

Original languageEnglish
Article number1026
Number of pages18
JournalEuropean Physical Journal C
Issue number11
Publication statusPublished - 24 Nov 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); DOE NP and NSF (USA). 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 NERSC (USA). 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 ARC and ARDC (Australia); 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 the Central Universities, and Sci. & Tech. Program of Guangzhou (China); RFBR, RSF and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Leverhulme Trust, the Royal Society and UKRI (United Kingdom).

Publisher Copyright:
© 2021, CERN for the benefit of the LHCb collaboration.

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)


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