European Physical Journal C: Particles and Fields (Apr 2022)

B-flavor tagging at Belle II

  • F. Abudinén,
  • N. Akopov,
  • A. Aloisio,
  • V. Babu,
  • Sw. Banerjee,
  • M. Bauer,
  • J. V. Bennett,
  • F. U. Bernlochner,
  • M. Bessner,
  • S. Bettarini,
  • T. Bilka,
  • S. Bilokin,
  • D. Biswas,
  • D. Bodrov,
  • J. Borah,
  • M. Bračko,
  • P. Branchini,
  • A. Budano,
  • M. Campajola,
  • G. Casarosa,
  • C. Cecchi,
  • R. Cheaib,
  • V. Chekelian,
  • C. Chen,
  • Y. Q. Chen,
  • H. -E. Cho,
  • S. Cunliffe,
  • G. De Nardo,
  • G. De Pietro,
  • R. de Sangro,
  • S. Dey,
  • A. Di Canto,
  • F. Di Capua,
  • T. V. Dong,
  • G. Dujany,
  • P. Ecker,
  • M. Eliachevitch,
  • T. Ferber,
  • F. Forti,
  • E. Ganiev,
  • A. Gaz,
  • M. Gelb,
  • J. Gemmler,
  • R. Godang,
  • P. Goldenzweig,
  • E. Graziani,
  • K. Hara,
  • A. Hershenhorn,
  • T. Higuchi,
  • E. C. Hill,
  • M. Hohmann,
  • T. Humair,
  • G. Inguglia,
  • H. Junkerkalefeld,
  • R. Karl,
  • Y. Kato,
  • T. Keck,
  • C. Kiesling,
  • C. -H. Kim,
  • S. Kohani,
  • I. Komarov,
  • T. M. G. Kraetzschmar,
  • P. Križan,
  • J. F. Krohn,
  • T. Kuhr,
  • J. Kumar,
  • K. Kumara,
  • S. Kurz,
  • S. Lacaprara,
  • C. La Licata,
  • M. Laurenza,
  • K. Lautenbach,
  • S. C. Lee,
  • K. Lieret,
  • L. Li Gioi,
  • Q. Y. Liu,
  • S. Longo,
  • M. Maggiora,
  • E. Manoni,
  • C. Marinas,
  • A. Martini,
  • F. Meier,
  • M. Merola,
  • F. Metzner,
  • M. Milesi,
  • K. Miyabayashi,
  • G. B. Mohanty,
  • F. Mueller,
  • C. Murphy,
  • E. R. Oxford,
  • S. -H. Park,
  • A. Passeri,
  • F. Pham,
  • L. E. Piilonen,
  • S. Pokharel,
  • M. T. Prim,
  • C. Pulvermacher,
  • P. Rados,
  • M. Ritter,
  • A. Rostomyan,
  • S. Sandilya,
  • L. Santelj,
  • Y. Sato,
  • A. J. Schwartz,
  • M. E. Sevior,
  • A. Soffer,
  • S. Spataro,
  • R. Stroili,
  • W. Sutcliffe,
  • D. Tagnani,
  • M. Takizawa,
  • U. Tamponi,
  • F. Tenchini,
  • E. Torassa,
  • P. Urquijo,
  • L. Vitale,
  • Y. Yusa,
  • L. Zani,
  • Q. D. Zhou,
  • R. Žlebčík,
  • A. Zupanc

DOI
https://doi.org/10.1140/epjc/s10052-022-10180-9
Journal volume & issue
Vol. 82, no. 4
pp. 1 – 29

Abstract

Read online

Abstract We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom ( ) mesons at Belle II. The algorithms provide essential inputs for measurements of quark-flavor mixing and charge-parity violation. We validate and evaluate the performance of the algorithms using hadronic decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb $$^{-1}$$ - 1 , collected at the resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be $$\begin{aligned} \varepsilon _\mathrm{eff} = \big (30.0 \pm 1.2(\text {stat}) \pm 0.4(\text {syst})\big )\% \end{aligned}$$ ε eff = ( 30.0 ± 1.2 ( stat ) ± 0.4 ( syst ) ) % for a category-based algorithm and $$\begin{aligned} \varepsilon _\mathrm{eff} = \big (28.8 \pm 1.2(\text {stat}) \pm 0.4(\text {syst})\big )\% \end{aligned}$$ ε eff = ( 28.8 ± 1.2 ( stat ) ± 0.4 ( syst ) ) % for a deep-learning-based algorithm.