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Test of lepton flavor universality and search for lepton flavor violation in B → Kℓℓ decays

Belle Collaboration; Choudhury, S.; Sandilya, S.; Trabelsi, K.; Giri, A.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; Babu, V.; Bahinipati, S.; Behera, P.; Beleño, C.; Belous, K.; Bennett, J.; Bernlochner, F.; Bessner, M.; Bhardwaj, V.; ... mehr

We present measurements of the branching fractions for the decays B → Kμ$^{+}$μ$^{-}$ and B → Ke$^{+}$e$^{-}$, and their ratio (RK), using a data sample of 711 fb$^{-1}$ that contains 772 × 10$^{6}$ B$\overline{B}$ events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e$^{+}$e$^{-}$ collider. The ratio RK is measured in five bins of dilepton invariant-mass-squared (q$^{2}$): q$^{2}$ ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (> 14.18) GeV$^{2}$/c$^{4}$, along with the whole q$^{2}$ region. The R$_{K}$ value for q$^{2}$ ∈ (1.0, 6.0) GeV$^{2}$/c$^{4}$ is 1.03$\substack{+0.28\\-0.24}$ ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for R$_{K}$ are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q$^{2}$ bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q$^{2}$ ∈ (1.0, 6.0) GeV$^{2}$/c$^{4}$ bin in the mode with muon final states. The measured differential branching fractions, dB/dq$^{2}$, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000131917
Veröffentlicht am 28.04.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Experimentelle Teilchenphysik (ETP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 1029-8479
KITopen-ID: 1000131917
Erschienen in Journal of high energy physics
Verlag Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Band 2021
Heft 3
Seiten Art. Nr.: 105
Vorab online veröffentlicht am 10.03.2021
Schlagwörter FCNC Interaction, Flavor physics, Flavour Changing Neutral Currents,B physics,e+-e- Experiments
Nachgewiesen in Scopus
Web of Science
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