https://doi.org/10.1140/epjc/s10052-022-10180-9
Special Article - Tools for Experiment and Theory
B-flavor tagging at Belle II
1
Aix Marseille Université, CNRS/IN2P3, CPPM, 13288, Marseille, France
2
Brookhaven National Laboratory, Upton, 11973, New York, USA
3
Carnegie Mellon University, 15213, Pittsburgh, PA, USA
4
Faculty of Mathematics and Physics, Charles University, 121 16, Prague, Czech Republic
5
Deutsches Elektronen-Synchrotron, 22607, Hamburg, Germany
6
Duke University, 27708, Durham, NC, USA
7
Institute of Theoretical and Applied Research (ITAR), Duy Tan University, 100000, Hanoi, Vietnam
8
The Graduate University for Advanced Studies (SOKENDAI), 240-0193, Hayama, Japan
9
Department of Physics and Institute of Natural Sciences, Hanyang University, 04763, Seoul, South Korea
10
High Energy Accelerator Research Organization (KEK), 305-0801, Tsukuba, Japan
11
J-PARC Branch, KEK Theory Center, High Energy Accelerator Research Organization (KEK), Tsukuba, 305-0801, Japan
12
Higher School of Economics (HSE), Moscow, 101000, Russian Federation
13
Hunan Normal University, 410081, Changsha, China
14
Indian Institute of Technology Guwahati, 781039, Guwahati, Assam, India
15
Indian Institute of Technology Hyderabad, 502285, Hyderabad, Telangana, India
16
Institute of High Energy Physics, 1050, Vienna, Austria
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Instituto de Fisica Corpuscular, 46980, Paterna, Spain
18
INFN Laboratori Nazionali di Frascati, 00044, Frascati, Italy
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INFN Sezione di Napoli, 80126, Naples, Italy
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INFN Sezione di Padova, 35131, Padua, Italy
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INFN Sezione di Perugia, 06123, Perugia, Italy
22
INFN Sezione di Pisa, 56127, Pisa, Italy
23
INFN Sezione di Roma Tre, 00146, Rome, Italy
24
INFN Sezione di Torino, 10125, Turin, Italy
25
INFN Sezione di Trieste, 34127, Trieste, Italy
26
Institut für Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131, Karlsruhe, Germany
27
Kyungpook National University, 41566, Daegu, South Korea
28
P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 119991, Moscow, Russian Federation
29
Ludwig Maximilians University, 80539, Munich, Germany
30
Iowa State University, 50011, Ames, IA, USA
31
Max-Planck-Institut für Physik, 80805, Munich, Germany
32
Graduate School of Science, Nagoya University, 464-8602, Nagoya, Japan
33
Kobayashi-Maskawa Institute, Nagoya University, 464-8602, Nagoya, Japan
34
Institute for Advanced Research, Nagoya University, Nagoya, 464-8602, Japan
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Nara Women’s University, Nara, 630-8506, Japan
36
Niigata University, Niigata, 950-2181, Japan
37
Meson Science Laboratory, Cluster for Pioneering Research, RIKEN, Saitama, 351-0198, Japan
38
Showa Pharmaceutical University, Tokyo, 194-8543, Japan
39
J. Stefan Institute, 1000, Ljubljana, Slovenia
40
Tata Institute of Fundamental Research, 400005, Mumbai, India
41
School of Physics and Astronomy, Tel Aviv University, 69978, Tel Aviv, Israel
42
Department of Physics, Tohoku University, 980-8578, Sendai, Japan
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Dipartimento di Scienze Fisiche, Università di Napoli Federico II, 80126, Naples, Italy
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Dipartimento di Fisica e Astronomia, Università di Padova, 35131, Padua, Italy
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Dipartimento di Fisica, Università di Perugia, 06123, Perugia, Italy
46
Dipartimento di Fisica, Università di Pisa, 56127, Pisa, Italy
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Dipartimento di Matematica e Fisica, Università di Roma Tre, 00146, Rome, Italy
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Dipartimento di Fisica, Università di Torino, 10125, Turin, Italy
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Dipartimento di Fisica, Università di Trieste, 34127, Trieste, Italy
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Université de Strasbourg, CNRS, IPHC, UMR 7178, 67037, Strasbourg, France
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University of Bonn, 53115, Bonn, Germany
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University of British Columbia, V6T 1Z1, Vancouver, BC, Canada
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University of Cincinnati, 45221, Cincinnati, OH, USA
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University of Hawaii, 96822, Honolulu, HI, USA
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Faculty of Mathematics and Physics, University of Ljubljana, 1000, Ljubljana, Slovenia
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University of Louisville, 40292, Louisville, KY, USA
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University of Maribor, 2000, Maribor, Slovenia
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School of Physics, University of Melbourne, 3010, Parkville, VIC, Australia
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University of Mississippi, 38677, University, MS, USA
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University of South Alabama, 36688, Mobile, AL, USA
61
Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 277-8583, Kashiwa, Japan
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Virginia Polytechnic Institute and State University, 24061, Blacksburg, VI, USA
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Wayne State University, 48202, Detroit, MI, USA
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Alikhanyan National Science Laboratory, 0036, Yerevan, Armenia
Received:
14
September
2021
Accepted:
1
March
2022
Published online:
1
April
2022
We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom (B) 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
B decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb-1, collected at the γ(4S) resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be 
for a category-based algorithm and 
for a deep-learning-based algorithm.
© The Author(s) 2022
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