Differential decay rate of B+JK+ with the LHCb Upgrade I experiment



Aaij, R, Abdelmotteleb, ASW, Beteta, C Abellan, Abudinen, F, Ackernley, T, Adefisoye, AA, Adeva, B, Adinolfi, M, Adlarson, P, Agapopoulou, C
et al (show 1176 more authors) (2026) Differential decay rate of B+JK+ with the LHCb Upgrade I experiment JOURNAL OF HIGH ENERGY PHYSICS, 2026 (4). ISSN 1126-6708, 1029-8479

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Abstract

The normalised decay rate of B+ → J/ψ(→ μ+μ)K+ is measured as a function of the lepton helicity angle using a data sample corresponding to an integrated luminosity of 1.1 fb−1 collected during October 2024 with the upgraded (Upgrade I) LHCb detector. This angular distribution can be parameterised by two coefficients, the forward-backward asymmetry, A<inf>FB</inf>, and the flatness parameter, F<inf>H</inf>, whose values are constrained by conservation of angular momentum. These coefficients are measured both integrated and differentially across various kinematic and detector-response variables, and the results are found to be in good agreement with expectations. These measurements show that the detector response of the LHCb Upgrade I experiment is understood to the precision required to reliably extract the angular coefficients associated with rare b → sμ+μ and b → dμ+μ transitions, which are particularly sensitive to physics beyond the Standard Model.

Item Type: Article
Uncontrolled Keywords: B Physics, Flavour Physics, Hadron-Hadron Scattering, Rare Decay
Divisions: Faculty of Humanities & Social Sciences
Faculty of Science & Engineering
Faculty of Science & Engineering > School of Physical Sciences
Faculty of Science & Engineering > School of Physical Sciences > Physics
Faculty of Humanities & Social Sciences > School of the Arts
Faculty of Humanities & Social Sciences > School of the Arts > Architecture
Depositing User: Symplectic Admin
Date Deposited: 26 May 2026 10:29
Last Modified: 26 May 2026 10:29
DOI: 10.1007/JHEP04(2026)170
Open Access URL: https://link.springer.com/content/pdf/10.1007/JHEP...
Related Websites:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3198622
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