Updated measurement of CP violation and polarisation in B s 0 → J / ψ K ¯ ∗ 892 0 decays
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13130_2025_Article_27465.pdf
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Author(s)
Aaij, R.
Abdelmotteleb, A. S. W.
Abellan Beteta, C.
Abudinén, F.
Ackernley, T.
Adefisoye, A. A.
Adeva, B.
Adinolfi, M.
Adlarson, P.
Agapopoulou, C.
Date Issued
October 21, 2025
Journal
Journal of High Energy Physics
Publisher
Springer Berlin Heidelberg
Citation
The LHCb collaboration., Aaij, R., Abdelmotteleb, A.S.W. et al. Updated measurement of CP violation and polarisation in B s 0 → J / ψ K ¯ ∗ 892 0 decays. J. High Energ. Phys. 2025, 173 (2025).
Version
Final published version
Abstract
A time-integrated angular analysis of the decay B s 0 → J / ψ K ¯ ∗ 892 0 , with J/ψ → μ+μ− and K ¯ ∗ 892 0 → K − π + , is presented. The analysis employs a sample of proton-proton collision data collected by the LHCb experiment during 2015–2018 at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. A simultaneous maximum-likelihood fit is performed to the angular distributions in bins of the K−π+ mass. This fit yields measurements of the CP-averaged polarisation fractions and CP asymmetries for the P-wave component of the K−π+ system. The longitudinal and parallel polarisation fractions are determined to be f0 = 0.534 ± 0.012 ± 0.009 and f|| = 0.211 ± 0.014 ± 0.005, respectively, where the first uncertainty is statistical and the second is systematic. The CP asymmetries are measured with 3–7% precision and are found to be consistent with zero. These measurements, along with an updated determination of the branching fraction relative to the B0 → J/ψK*0 decay, are combined with previous LHCb results, providing the most precise values for these observables to date.
MIT Department
Massachusetts Institute of Technology. Laboratory for Nuclear Science
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1007/JHEP10(2025)173
