Updated measurement of CP violation and polarisation in Bs0 → J/ψ(K)over-bar*(892)0 decays



Aaij, R, Abdelmotteleb, ASW, Beteta, C Abellan, Abudinen, F, Ackernley, T, Adefisoye, AA, Adeva, B, Adinolfi, M, Adlarson, P, Agapopoulou, C
et al (show 1157 more authors) (2025) Updated measurement of CP violation and polarisation in Bs0 → J/ψ(K)over-bar*(892)0 decays JOURNAL OF HIGH ENERGY PHYSICS, 2025 (10). 173-. ISSN 1126-6708, 1029-8479

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Abstract

A time-integrated angular analysis of the decay Bs0→J/ψK¯∗8920, with J/ψ → μ+μ and K¯∗8920→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 Kπ+ mass. This fit yields measurements of the CP-averaged polarisation fractions and CP asymmetries for the P-wave component of the Kπ+ system. The longitudinal and parallel polarisation fractions are determined to be f<inf>0</inf> = 0.534 ± 0.012 ± 0.009 and f<inf>||</inf> = 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.

Item Type: Article
Uncontrolled Keywords: B Physics, CP Violation, Hadron-Hadron Scattering, Polarization
Divisions: Faculty of Humanities & Social Sciences
Faculty of Science & Engineering
Faculty of Science & Engineering > School of 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
Faculty of Science & Engineering > School of Engineering > Civil and Environmental Engineering
Depositing User: Symplectic Admin
Date Deposited: 08 Dec 2025 16:42
Last Modified: 16 Jun 2026 07:10
DOI: 10.1007/JHEP10(2025)173
Open Access URL: https://link.springer.com/content/pdf/10.1007/JHEP...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3195987
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