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, AFB, and the flatness parameter, FH, 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.

Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinen, F., Ackernley, T., Adefisoye, A., et al. (2026). Differential decay rate of B+→ J/ψK+ with the LHCb Upgrade I experiment. JOURNAL OF HIGH ENERGY PHYSICS, 2026(4) [10.1007/JHEP04(2026)170].

Differential decay rate of B+→ J/ψK+ with the LHCb Upgrade I experiment

Anelli A.;Borsato M.;Calvi M.;Capelli S.;Carniti P.;Falcao L. N.;Fazzini D.;Gotti C.;Kirsebom V. S.;Malentacca L.;Martinazzoli L.;Martinelli M.;Minotti A.;Pizzichemi M.;Salomoni M.;
2026

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, AFB, and the flatness parameter, FH, 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.
Articolo in rivista - Articolo scientifico
B Physics; Flavour Physics; Hadron-Hadron Scattering; Rare Decay;
English
22-apr-2026
2026
2026
4
170
none
Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinen, F., Ackernley, T., Adefisoye, A., et al. (2026). Differential decay rate of B+→ J/ψK+ with the LHCb Upgrade I experiment. JOURNAL OF HIGH ENERGY PHYSICS, 2026(4) [10.1007/JHEP04(2026)170].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/609584
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