BELLE2-CONF-PH-2021-011

Belle II Collaboration

#
Measurement of the $B^{-}\rightarrow D^{0}\ell^{-}\bar{\nu}_{\ell}$ Branching
Fraction in 62.8 fb-1 of Belle II data

F. Abudinén  INFN Sezione di Trieste, I-34127 Trieste, Italy  I. Adachi  High
Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  The
Graduate University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan
R. Adak  Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and
Institute of Modern Physics, Fudan University, Shanghai 200443, China  K.
Adamczyk  H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342,
Poland  L. Aggarwal  Panjab University, Chandigarh 160014, India  P. Ahlburg
University of Bonn, 53115 Bonn, Germany  H. Ahmed  St. Francis Xavier
University, Antigonish, Nova Scotia, B2G 2W5, Canada  J. K. Ahn  Korea
University, Seoul 02841, South Korea  H. Aihara  Department of Physics,
University of Tokyo, Tokyo 113-0033, Japan  N. Akopov  Alikhanyan National
Science Laboratory, Yerevan 0036, Armenia  A. Aloisio  Dipartimento di Scienze
Fisiche, Università di Napoli Federico II, I-80126 Napoli, Italy  INFN Sezione
di Napoli, I-80126 Napoli, Italy  F. Ameli  INFN Sezione di Roma, I-00185
Roma, Italy  L. Andricek  Semiconductor Laboratory of the Max Planck Society,
81739 München, Germany  N. Anh Ky  Institute of Physics, Vietnam Academy of
Science and Technology (VAST), Hanoi, Vietnam  Institute of Theoretical and
Applied Research (ITAR), Duy Tan University, Hanoi 100000, Vietnam  D. M.
Asner  Brookhaven National Laboratory, Upton, New York 11973, U.S.A.  H.
Atmacan  University of Cincinnati, Cincinnati, Ohio 45221, U.S.A.  V.
Aulchenko  Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090,
Russian Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  T. Aushev  National Research University Higher School of
Economics, Moscow 101000, Russian Federation  V. Aushev  Taras Shevchenko
National Univ. of Kiev, Kiev, Ukraine  T. Aziz  Tata Institute of Fundamental
Research, Mumbai 400005, India  V. Babu  Deutsches Elektronen–Synchrotron,
22607 Hamburg, Germany  S. Bacher  H. Niewodniczanski Institute of Nuclear
Physics, Krakow 31-342, Poland  H. Bae  Department of Physics, University of
Tokyo, Tokyo 113-0033, Japan  S. Baehr  Institut für Experimentelle
Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
S. Bahinipati  Indian Institute of Technology Bhubaneswar, Satya Nagar 751007,
India  A. M. Bakich  School of Physics, University of Sydney, New South Wales
2006, Australia  P. Bambade  Université Paris-Saclay, CNRS/IN2P3, IJCLab,
91405 Orsay, France  Sw. Banerjee  University of Louisville, Louisville,
Kentucky 40292, U.S.A.  S. Bansal  Panjab University, Chandigarh 160014, India
M. Barrett  High Energy Accelerator Research Organization (KEK), Tsukuba
305-0801, Japan  G. Batignani  Dipartimento di Fisica, Università di Pisa,
I-56127 Pisa, Italy  INFN Sezione di Pisa, I-56127 Pisa, Italy  J. Baudot
Université de Strasbourg, CNRS, IPHC, UMR 7178, 67037 Strasbourg, France  M.
Bauer  Institut für Experimentelle Teilchenphysik, Karlsruher Institut für
Technologie, 76131 Karlsruhe, Germany  A. Baur  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  A. Beaulieu  University of
Victoria, Victoria, British Columbia, V8W 3P6, Canada  J. Becker  Institut für
Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131
Karlsruhe, Germany  P. K. Behera  Indian Institute of Technology Madras,
Chennai 600036, India  J. V. Bennett  University of Mississippi, University,
Mississippi 38677, U.S.A.  E. Bernieri  INFN Sezione di Roma Tre, I-00146
Roma, Italy  F. U. Bernlochner  University of Bonn, 53115 Bonn, Germany  M.
Bertemes  Institute of High Energy Physics, Vienna 1050, Austria  E. Bertholet
Tel Aviv University, School of Physics and Astronomy, Tel Aviv, 69978, Israel
M. Bessner  University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  S. Bettarini
Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy  INFN Sezione
di Pisa, I-56127 Pisa, Italy  V. Bhardwaj  Indian Institute of Science
Education and Research Mohali, SAS Nagar, 140306, India  B. Bhuyan  Indian
Institute of Technology Guwahati, Assam 781039, India  F. Bianchi
Dipartimento di Fisica, Università di Torino, I-10125 Torino, Italy  INFN
Sezione di Torino, I-10125 Torino, Italy  T. Bilka  Faculty of Mathematics and
Physics, Charles University, 121 16 Prague, Czech Republic  S. Bilokin  Ludwig
Maximilians University, 80539 Munich, Germany  D. Biswas  University of
Louisville, Louisville, Kentucky 40292, U.S.A.  A. Bobrov  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk
State University, Novosibirsk 630090, Russian Federation  D. Bodrov  National
Research University Higher School of Economics, Moscow 101000, Russian
Federation  P.N. Lebedev Physical Institute of the Russian Academy of
Sciences, Moscow 119991, Russian Federation  A. Bolz  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  A. Bondar  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk
State University, Novosibirsk 630090, Russian Federation  G. Bonvicini  Wayne
State University, Detroit, Michigan 48202, U.S.A.  A. Bozek  H.
Niewodniczanski Institute of Nuclear Physics, Krakow 31-342, Poland  M. Bračko
Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000
Maribor, Slovenia  J. Stefan Institute, 1000 Ljubljana, Slovenia  P. Branchini
INFN Sezione di Roma Tre, I-00146 Roma, Italy  N. Braun  Institut für
Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131
Karlsruhe, Germany  R. A. Briere  Carnegie Mellon University, Pittsburgh,
Pennsylvania 15213, U.S.A.  T. E. Browder  University of Hawaii, Honolulu,
Hawaii 96822, U.S.A.  D. N. Brown  University of Louisville, Louisville,
Kentucky 40292, U.S.A.  A. Budano  INFN Sezione di Roma Tre, I-00146 Roma,
Italy  L. Burmistrov  Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405
Orsay, France  S. Bussino  Dipartimento di Matematica e Fisica, Università di
Roma Tre, I-00146 Roma, Italy  INFN Sezione di Roma Tre, I-00146 Roma, Italy
M. Campajola  Dipartimento di Scienze Fisiche, Università di Napoli Federico
II, I-80126 Napoli, Italy  INFN Sezione di Napoli, I-80126 Napoli, Italy  L.
Cao  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  G. Caria
School of Physics, University of Melbourne, Victoria 3010, Australia  G.
Casarosa  Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy
INFN Sezione di Pisa, I-56127 Pisa, Italy  C. Cecchi  Dipartimento di Fisica,
Università di Perugia, I-06123 Perugia, Italy  INFN Sezione di Perugia,
I-06123 Perugia, Italy  D. Červenkov  Faculty of Mathematics and Physics,
Charles University, 121 16 Prague, Czech Republic  M.-C. Chang  Department of
Physics, Fu Jen Catholic University, Taipei 24205, Taiwan  P. Chang
Department of Physics, National Taiwan University, Taipei 10617, Taiwan  R.
Cheaib  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  V. Chekelian
Max-Planck-Institut für Physik, 80805 München, Germany  C. Chen  Iowa State
University, Ames, Iowa 50011, U.S.A.  Y. Q. Chen  University of Science and
Technology of China, Hefei 230026, China  Y.-T. Chen  Department of Physics,
National Taiwan University, Taipei 10617, Taiwan  B. G. Cheon  Department of
Physics and Institute of Natural Sciences, Hanyang University, Seoul 04763,
South Korea  K. Chilikin  P.N. Lebedev Physical Institute of the Russian
Academy of Sciences, Moscow 119991, Russian Federation  K. Chirapatpimol
Chiang Mai University, Chiang Mai 50202, Thailand  H.-E. Cho  Department of
Physics and Institute of Natural Sciences, Hanyang University, Seoul 04763,
South Korea  K. Cho  Korea Institute of Science and Technology Information,
Daejeon 34141, South Korea  S.-J. Cho  Yonsei University, Seoul 03722, South
Korea  S.-K. Choi  Gyeongsang National University, Jinju 52828, South Korea
S. Choudhury  Indian Institute of Technology Hyderabad, Telangana 502285,
India  D. Cinabro  Wayne State University, Detroit, Michigan 48202, U.S.A.  L.
Corona  Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy  INFN
Sezione di Pisa, I-56127 Pisa, Italy  L. M. Cremaldi  University of
Mississippi, University, Mississippi 38677, U.S.A.  D. Cuesta  Université de
Strasbourg, CNRS, IPHC, UMR 7178, 67037 Strasbourg, France  S. Cunliffe
Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  T. Czank  Kavli
Institute for the Physics and Mathematics of the Universe (WPI), University of
Tokyo, Kashiwa 277-8583, Japan  N. Dash  Indian Institute of Technology
Madras, Chennai 600036, India  F. Dattola  Deutsches Elektronen–Synchrotron,
22607 Hamburg, Germany  E. De La Cruz-Burelo  Centro de Investigacion y de
Estudios Avanzados del Instituto Politecnico Nacional, Mexico City 07360,
Mexico  G. de Marino  Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405
Orsay, France  G. De Nardo  Dipartimento di Scienze Fisiche, Università di
Napoli Federico II, I-80126 Napoli, Italy  INFN Sezione di Napoli, I-80126
Napoli, Italy  M. De Nuccio  Deutsches Elektronen–Synchrotron, 22607 Hamburg,
Germany  G. De Pietro  INFN Sezione di Roma Tre, I-00146 Roma, Italy  R. de
Sangro  INFN Laboratori Nazionali di Frascati, I-00044 Frascati, Italy  B.
Deschamps  University of Bonn, 53115 Bonn, Germany  M. Destefanis
Dipartimento di Fisica, Università di Torino, I-10125 Torino, Italy  INFN
Sezione di Torino, I-10125 Torino, Italy  S. Dey  Tel Aviv University, School
of Physics and Astronomy, Tel Aviv, 69978, Israel  A. De Yta-Hernandez  Centro
de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional,
Mexico City 07360, Mexico  A. Di Canto  Brookhaven National Laboratory, Upton,
New York 11973, U.S.A.  F. Di Capua  Dipartimento di Scienze Fisiche,
Università di Napoli Federico II, I-80126 Napoli, Italy  INFN Sezione di
Napoli, I-80126 Napoli, Italy  S. Di Carlo  Université Paris-Saclay,
CNRS/IN2P3, IJCLab, 91405 Orsay, France  J. Dingfelder  University of Bonn,
53115 Bonn, Germany  Z. Doležal  Faculty of Mathematics and Physics, Charles
University, 121 16 Prague, Czech Republic  I. Domínguez Jiménez  Universidad
Autonoma de Sinaloa, Sinaloa 80000, Mexico  T. V. Dong  Institute of
Theoretical and Applied Research (ITAR), Duy Tan University, Hanoi 100000,
Vietnam  M. Dorigo  Dipartimento di Fisica, Università di Trieste, I-34127
Trieste, Italy  INFN Sezione di Trieste, I-34127 Trieste, Italy  K. Dort
Justus-Liebig-Universität Gießen, 35392 Gießen, Germany  D. Dossett  School of
Physics, University of Melbourne, Victoria 3010, Australia  S. Dubey
University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  S. Duell  University of
Bonn, 53115 Bonn, Germany  G. Dujany  Université de Strasbourg, CNRS, IPHC,
UMR 7178, 67037 Strasbourg, France  S. Eidelman  Budker Institute of Nuclear
Physics SB RAS, Novosibirsk 630090, Russian Federation  P.N. Lebedev Physical
Institute of the Russian Academy of Sciences, Moscow 119991, Russian
Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  M. Eliachevitch  University of Bonn, 53115 Bonn, Germany  D.
Epifanov  Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090,
Russian Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  J. E. Fast  Pacific Northwest National Laboratory, Richland,
Washington 99352, U.S.A.  T. Ferber  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  D. Ferlewicz  School of Physics, University of Melbourne,
Victoria 3010, Australia  T. Fillinger  Université de Strasbourg, CNRS, IPHC,
UMR 7178, 67037 Strasbourg, France  G. Finocchiaro  INFN Laboratori Nazionali
di Frascati, I-00044 Frascati, Italy  S. Fiore  INFN Sezione di Roma, I-00185
Roma, Italy  P. Fischer  University of Heidelberg, 68131 Mannheim, Germany  A.
Fodor  McGill University, Montréal, Québec, H3A 2T8, Canada  F. Forti
Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy  INFN Sezione
di Pisa, I-56127 Pisa, Italy  A. Frey  II. Physikalisches Institut, Georg-
August-Universität Göttingen, 37073 Göttingen, Germany  M. Friedl  Institute
of High Energy Physics, Vienna 1050, Austria  B. G. Fulsom  Pacific Northwest
National Laboratory, Richland, Washington 99352, U.S.A.  M. Gabriel  Max-
Planck-Institut für Physik, 80805 München, Germany  A. Gabrielli  Dipartimento
di Fisica, Università di Trieste, I-34127 Trieste, Italy  INFN Sezione di
Trieste, I-34127 Trieste, Italy  N. Gabyshev  Budker Institute of Nuclear
Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk State
University, Novosibirsk 630090, Russian Federation  E. Ganiev  Dipartimento di
Fisica, Università di Trieste, I-34127 Trieste, Italy  INFN Sezione di
Trieste, I-34127 Trieste, Italy  M. Garcia-Hernandez  Centro de Investigacion
y de Estudios Avanzados del Instituto Politecnico Nacional, Mexico City 07360,
Mexico  R. Garg  Panjab University, Chandigarh 160014, India  A. Garmash
Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russian
Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  V. Gaur  Virginia Polytechnic Institute and State University,
Blacksburg, Virginia 24061, U.S.A.  A. Gaz  Dipartimento di Fisica e
Astronomia, Università di Padova, I-35131 Padova, Italy  INFN Sezione di
Padova, I-35131 Padova, Italy  U. Gebauer  II. Physikalisches Institut, Georg-
August-Universität Göttingen, 37073 Göttingen, Germany  A. Gellrich  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  J. Gemmler  Institut für
Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131
Karlsruhe, Germany  T. Geßler  Justus-Liebig-Universität Gießen, 35392 Gießen,
Germany  D. Getzkow  Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
R. Giordano  Dipartimento di Scienze Fisiche, Università di Napoli Federico
II, I-80126 Napoli, Italy  INFN Sezione di Napoli, I-80126 Napoli, Italy  A.
Giri  Indian Institute of Technology Hyderabad, Telangana 502285, India  A.
Glazov  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  B. Gobbo
INFN Sezione di Trieste, I-34127 Trieste, Italy  R. Godang  University of
South Alabama, Mobile, Alabama 36688, U.S.A.  P. Goldenzweig  Institut für
Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131
Karlsruhe, Germany  B. Golob  Faculty of Mathematics and Physics, University
of Ljubljana, 1000 Ljubljana, Slovenia  J. Stefan Institute, 1000 Ljubljana,
Slovenia  P. Gomis  Instituto de Fisica Corpuscular, Paterna 46980, Spain  G.
Gong  University of Science and Technology of China, Hefei 230026, China  P.
Grace  Department of Physics, University of Adelaide, Adelaide, South
Australia 5005, Australia  W. Gradl  Institut für Kernphysik, Johannes
Gutenberg-Universität Mainz, D-55099 Mainz, Germany  E. Graziani  INFN Sezione
di Roma Tre, I-00146 Roma, Italy  D. Greenwald  Department of Physics,
Technische Universität München, 85748 Garching, Germany  T. Gu  University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, U.S.A.  Y. Guan  University of
Cincinnati, Cincinnati, Ohio 45221, U.S.A.  K. Gudkova  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk
State University, Novosibirsk 630090, Russian Federation  C. Hadjivasiliou
Pacific Northwest National Laboratory, Richland, Washington 99352, U.S.A.  S.
Halder  Tata Institute of Fundamental Research, Mumbai 400005, India  K. Hara
High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
The Graduate University for Advanced Studies (SOKENDAI), Hayama 240-0193,
Japan  T. Hara  High Energy Accelerator Research Organization (KEK), Tsukuba
305-0801, Japan  The Graduate University for Advanced Studies (SOKENDAI),
Hayama 240-0193, Japan  O. Hartbrich  University of Hawaii, Honolulu, Hawaii
96822, U.S.A.  K. Hayasaka  Niigata University, Niigata 950-2181, Japan  H.
Hayashii  Nara Women’s University, Nara 630-8506, Japan  S. Hazra  Tata
Institute of Fundamental Research, Mumbai 400005, India  C. Hearty  University
of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada  Institute
of Particle Physics (Canada), Victoria, British Columbia V8W 2Y2, Canada  M.
T. Hedges  University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  I. Heredia de
la Cruz  Centro de Investigacion y de Estudios Avanzados del Instituto
Politecnico Nacional, Mexico City 07360, Mexico  Consejo Nacional de Ciencia y
Tecnología, Mexico City 03940, Mexico  M. Hernández Villanueva  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  A. Hershenhorn  University of
British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada  T. Higuchi
Kavli Institute for the Physics and Mathematics of the Universe (WPI),
University of Tokyo, Kashiwa 277-8583, Japan  E. C. Hill  University of
British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada  H. Hirata
Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan  M. Hoek
Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz,
Germany  M. Hohmann  School of Physics, University of Melbourne, Victoria
3010, Australia  S. Hollitt  Department of Physics, University of Adelaide,
Adelaide, South Australia 5005, Australia  T. Hotta  Research Center for
Nuclear Physics, Osaka University, Osaka 567-0047, Japan  C.-L. Hsu  School of
Physics, University of Sydney, New South Wales 2006, Australia  Y. Hu
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049,
China  K. Huang  Department of Physics, National Taiwan University, Taipei
10617, Taiwan  T. Humair  Max-Planck-Institut für Physik, 80805 München,
Germany  T. Iijima  Graduate School of Science, Nagoya University, Nagoya
464-8602, Japan  Kobayashi-Maskawa Institute, Nagoya University, Nagoya
464-8602, Japan  K. Inami  Graduate School of Science, Nagoya University,
Nagoya 464-8602, Japan  G. Inguglia  Institute of High Energy Physics, Vienna
1050, Austria  J. Irakkathil Jabbar  Institut für Experimentelle
Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
A. Ishikawa  High Energy Accelerator Research Organization (KEK), Tsukuba
305-0801, Japan  The Graduate University for Advanced Studies (SOKENDAI),
Hayama 240-0193, Japan  R. Itoh  High Energy Accelerator Research Organization
(KEK), Tsukuba 305-0801, Japan  The Graduate University for Advanced Studies
(SOKENDAI), Hayama 240-0193, Japan  M. Iwasaki  Osaka City University, Osaka
558-8585, Japan  Y. Iwasaki  High Energy Accelerator Research Organization
(KEK), Tsukuba 305-0801, Japan  S. Iwata  Tokyo Metropolitan University, Tokyo
192-0397, Japan  P. Jackson  Department of Physics, University of Adelaide,
Adelaide, South Australia 5005, Australia  W. W. Jacobs  Indiana University,
Bloomington, Indiana 47408, U.S.A.  I. Jaegle  University of Florida,
Gainesville, Florida 32611, U.S.A.  D. E. Jaffe  Brookhaven National
Laboratory, Upton, New York 11973, U.S.A.  E.-J. Jang  Gyeongsang National
University, Jinju 52828, South Korea  M. Jeandron  University of Mississippi,
University, Mississippi 38677, U.S.A.  H. B. Jeon  Kyungpook National
University, Daegu 41566, South Korea  S. Jia  Key Laboratory of Nuclear
Physics and Ion-beam Application (MOE) and Institute of Modern Physics, Fudan
University, Shanghai 200443, China  Y. Jin  INFN Sezione di Trieste, I-34127
Trieste, Italy  C. Joo  Kavli Institute for the Physics and Mathematics of the
Universe (WPI), University of Tokyo, Kashiwa 277-8583, Japan  K. K. Joo
Chonnam National University, Gwangju 61186, South Korea  H. Junkerkalefeld
University of Bonn, 53115 Bonn, Germany  I. Kadenko  Taras Shevchenko National
Univ. of Kiev, Kiev, Ukraine  J. Kahn  Institut für Experimentelle
Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
H. Kakuno  Tokyo Metropolitan University, Tokyo 192-0397, Japan  A. B. Kaliyar
Tata Institute of Fundamental Research, Mumbai 400005, India  J. Kandra
Faculty of Mathematics and Physics, Charles University, 121 16 Prague, Czech
Republic  K. H. Kang  Kyungpook National University, Daegu 41566, South Korea
P. Kapusta  H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342,
Poland  R. Karl  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  G.
Karyan  Alikhanyan National Science Laboratory, Yerevan 0036, Armenia  Y. Kato
Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
Kobayashi-Maskawa Institute, Nagoya University, Nagoya 464-8602, Japan  H.
Kawai  Chiba University, Chiba 263-8522, Japan  T. Kawasaki  Kitasato
University, Sagamihara 252-0373, Japan  C. Ketter  University of Hawaii,
Honolulu, Hawaii 96822, U.S.A.  H. Kichimi  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  C. Kiesling  Max-Planck-Institut
für Physik, 80805 München, Germany  B. H. Kim  Seoul National University,
Seoul 08826, South Korea  C.-H. Kim  Department of Physics and Institute of
Natural Sciences, Hanyang University, Seoul 04763, South Korea  D. Y. Kim
Soongsil University, Seoul 06978, South Korea  H. J. Kim  Kyungpook National
University, Daegu 41566, South Korea  K.-H. Kim  Yonsei University, Seoul
03722, South Korea  K. Kim  Korea University, Seoul 02841, South Korea  S.-H.
Kim  Seoul National University, Seoul 08826, South Korea  Y.-K. Kim  Yonsei
University, Seoul 03722, South Korea  Y. Kim  Korea University, Seoul 02841,
South Korea  T. D. Kimmel  Virginia Polytechnic Institute and State
University, Blacksburg, Virginia 24061, U.S.A.  H. Kindo  High Energy
Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate
University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  K.
Kinoshita  University of Cincinnati, Cincinnati, Ohio 45221, U.S.A.  C.
Kleinwort  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  B. Knysh
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France  P. Kodyš
Faculty of Mathematics and Physics, Charles University, 121 16 Prague, Czech
Republic  T. Koga  High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan  S. Kohani  University of Hawaii, Honolulu, Hawaii
96822, U.S.A.  I. Komarov  Deutsches Elektronen–Synchrotron, 22607 Hamburg,
Germany  T. Konno  Kitasato University, Sagamihara 252-0373, Japan  A. Korobov
Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russian
Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  S. Korpar  Faculty of Chemistry and Chemical Engineering,
University of Maribor, 2000 Maribor, Slovenia  J. Stefan Institute, 1000
Ljubljana, Slovenia  N. Kovalchuk  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  E. Kovalenko  Budker Institute of Nuclear Physics SB RAS,
Novosibirsk 630090, Russian Federation  Novosibirsk State University,
Novosibirsk 630090, Russian Federation  R. Kowalewski  University of Victoria,
Victoria, British Columbia, V8W 3P6, Canada  T. M. G. Kraetzschmar  Max-
Planck-Institut für Physik, 80805 München, Germany  F. Krinner  Max-Planck-
Institut für Physik, 80805 München, Germany  P. Križan  Faculty of Mathematics
and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia  J. Stefan
Institute, 1000 Ljubljana, Slovenia  R. Kroeger  University of Mississippi,
University, Mississippi 38677, U.S.A.  J. F. Krohn  School of Physics,
University of Melbourne, Victoria 3010, Australia  P. Krokovny  Budker
Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation
Novosibirsk State University, Novosibirsk 630090, Russian Federation  H.
Krüger  University of Bonn, 53115 Bonn, Germany  W. Kuehn  Justus-Liebig-
Universität Gießen, 35392 Gießen, Germany  T. Kuhr  Ludwig Maximilians
University, 80539 Munich, Germany  J. Kumar  Carnegie Mellon University,
Pittsburgh, Pennsylvania 15213, U.S.A.  M. Kumar  Malaviya National Institute
of Technology Jaipur, Jaipur 302017, India  R. Kumar  Punjab Agricultural
University, Ludhiana 141004, India  K. Kumara  Wayne State University,
Detroit, Michigan 48202, U.S.A.  T. Kumita  Tokyo Metropolitan University,
Tokyo 192-0397, Japan  T. Kunigo  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  M. Künzel  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  Ludwig Maximilians University,
80539 Munich, Germany  S. Kurz  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  A. Kuzmin  Budker Institute of Nuclear Physics SB RAS,
Novosibirsk 630090, Russian Federation  Novosibirsk State University,
Novosibirsk 630090, Russian Federation  P. Kvasnička  Faculty of Mathematics
and Physics, Charles University, 121 16 Prague, Czech Republic  Y.-J. Kwon
Yonsei University, Seoul 03722, South Korea  S. Lacaprara  INFN Sezione di
Padova, I-35131 Padova, Italy  Y.-T. Lai  Kavli Institute for the Physics and
Mathematics of the Universe (WPI), University of Tokyo, Kashiwa 277-8583,
Japan  C. La Licata  Kavli Institute for the Physics and Mathematics of the
Universe (WPI), University of Tokyo, Kashiwa 277-8583, Japan  K. Lalwani
Malaviya National Institute of Technology Jaipur, Jaipur 302017, India  T. Lam
Virginia Polytechnic Institute and State University, Blacksburg, Virginia
24061, U.S.A.  L. Lanceri  INFN Sezione di Trieste, I-34127 Trieste, Italy  J.
S. Lange  Justus-Liebig-Universität Gießen, 35392 Gießen, Germany  M. Laurenza
Dipartimento di Matematica e Fisica, Università di Roma Tre, I-00146 Roma,
Italy  INFN Sezione di Roma Tre, I-00146 Roma, Italy  K. Lautenbach  Aix
Marseille Université, CNRS/IN2P3, CPPM, 13288 Marseille, France  P. J. Laycock
Brookhaven National Laboratory, Upton, New York 11973, U.S.A.  F. R. Le
Diberder  Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
I.-S. Lee  Department of Physics and Institute of Natural Sciences, Hanyang
University, Seoul 04763, South Korea  S. C. Lee  Kyungpook National
University, Daegu 41566, South Korea  P. Leitl  Max-Planck-Institut für
Physik, 80805 München, Germany  D. Levit  Department of Physics, Technische
Universität München, 85748 Garching, Germany  P. M. Lewis  University of Bonn,
53115 Bonn, Germany  C. Li  Liaoning Normal University, Dalian 116029, China
L. K. Li  University of Cincinnati, Cincinnati, Ohio 45221, U.S.A.  S. X. Li
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute
of Modern Physics, Fudan University, Shanghai 200443, China  Y. B. Li  Key
Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute of
Modern Physics, Fudan University, Shanghai 200443, China  J. Libby  Indian
Institute of Technology Madras, Chennai 600036, India  K. Lieret  Ludwig
Maximilians University, 80539 Munich, Germany  J. Lin  Department of Physics,
National Taiwan University, Taipei 10617, Taiwan  Z. Liptak  Hiroshima
University, Higashi-Hiroshima, Hiroshima 739-8530, Japan  Q. Y. Liu  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  Z. A. Liu  Institute of High
Energy Physics, Chinese Academy of Sciences, Beijing 100049, China  D.
Liventsev  Wayne State University, Detroit, Michigan 48202, U.S.A.  High
Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  S.
Longo  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  A. Loos
University of South Carolina, Columbia, South Carolina 29208, U.S.A.  A. Lozar
J. Stefan Institute, 1000 Ljubljana, Slovenia  P. Lu  Department of Physics,
National Taiwan University, Taipei 10617, Taiwan  T. Lueck  Ludwig Maximilians
University, 80539 Munich, Germany  F. Luetticke  University of Bonn, 53115
Bonn, Germany  T. Luo  Key Laboratory of Nuclear Physics and Ion-beam
Application (MOE) and Institute of Modern Physics, Fudan University, Shanghai
200443, China  C. Lyu  University of Bonn, 53115 Bonn, Germany  C. MacQueen
School of Physics, University of Melbourne, Victoria 3010, Australia  Y. Maeda
Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
Kobayashi-Maskawa Institute, Nagoya University, Nagoya 464-8602, Japan  M.
Maggiora  Dipartimento di Fisica, Università di Torino, I-10125 Torino, Italy
INFN Sezione di Torino, I-10125 Torino, Italy  S. Maity  Indian Institute of
Technology Bhubaneswar, Satya Nagar 751007, India  R. Manfredi  Dipartimento
di Fisica, Università di Trieste, I-34127 Trieste, Italy  INFN Sezione di
Trieste, I-34127 Trieste, Italy  E. Manoni  INFN Sezione di Perugia, I-06123
Perugia, Italy  S. Marcello  Dipartimento di Fisica, Università di Torino,
I-10125 Torino, Italy  INFN Sezione di Torino, I-10125 Torino, Italy  C.
Marinas  Instituto de Fisica Corpuscular, Paterna 46980, Spain  A. Martini
Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  M. Masuda
Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan
Research Center for Nuclear Physics, Osaka University, Osaka 567-0047, Japan
T. Matsuda  University of Miyazaki, Miyazaki 889-2192, Japan  K. Matsuoka
High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
D. Matvienko  Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090,
Russian Federation  P.N. Lebedev Physical Institute of the Russian Academy of
Sciences, Moscow 119991, Russian Federation  Novosibirsk State University,
Novosibirsk 630090, Russian Federation  J. A. McKenna  University of British
Columbia, Vancouver, British Columbia, V6T 1Z1, Canada  J. McNeil  University
of Florida, Gainesville, Florida 32611, U.S.A.  F. Meggendorfer  Max-Planck-
Institut für Physik, 80805 München, Germany  J. C. Mei  Key Laboratory of
Nuclear Physics and Ion-beam Application (MOE) and Institute of Modern
Physics, Fudan University, Shanghai 200443, China  F. Meier  Duke University,
Durham, North Carolina 27708, U.S.A.  M. Merola  Dipartimento di Scienze
Fisiche, Università di Napoli Federico II, I-80126 Napoli, Italy  INFN Sezione
di Napoli, I-80126 Napoli, Italy  F. Metzner  Institut für Experimentelle
Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
M. Milesi  School of Physics, University of Melbourne, Victoria 3010,
Australia  C. Miller  University of Victoria, Victoria, British Columbia, V8W
3P6, Canada  K. Miyabayashi  Nara Women’s University, Nara 630-8506, Japan  H.
Miyake  High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801,
Japan  The Graduate University for Advanced Studies (SOKENDAI), Hayama
240-0193, Japan  H. Miyata  Niigata University, Niigata 950-2181, Japan  R.
Mizuk  P.N. Lebedev Physical Institute of the Russian Academy of Sciences,
Moscow 119991, Russian Federation  National Research University Higher School
of Economics, Moscow 101000, Russian Federation  K. Azmi  National Centre for
Particle Physics, University Malaya, 50603 Kuala Lumpur, Malaysia  G. B.
Mohanty  Tata Institute of Fundamental Research, Mumbai 400005, India  H. Moon
Korea University, Seoul 02841, South Korea  T. Moon  Seoul National
University, Seoul 08826, South Korea  J. A. Mora Grimaldo  Department of
Physics, University of Tokyo, Tokyo 113-0033, Japan  T. Morii  Kavli Institute
for the Physics and Mathematics of the Universe (WPI), University of Tokyo,
Kashiwa 277-8583, Japan  H.-G. Moser  Max-Planck-Institut für Physik, 80805
München, Germany  M. Mrvar  Institute of High Energy Physics, Vienna 1050,
Austria  F. Mueller  Max-Planck-Institut für Physik, 80805 München, Germany
F. J. Müller  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  Th.
Muller  Institut für Experimentelle Teilchenphysik, Karlsruher Institut für
Technologie, 76131 Karlsruhe, Germany  G. Muroyama  Graduate School of
Science, Nagoya University, Nagoya 464-8602, Japan  C. Murphy  Kavli Institute
for the Physics and Mathematics of the Universe (WPI), University of Tokyo,
Kashiwa 277-8583, Japan  R. Mussa  INFN Sezione di Torino, I-10125 Torino,
Italy  I. Nakamura  High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan  The Graduate University for Advanced Studies
(SOKENDAI), Hayama 240-0193, Japan  K. R. Nakamura  High Energy Accelerator
Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University
for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  E. Nakano  Osaka City
University, Osaka 558-8585, Japan  M. Nakao  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University for
Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  H. Nakayama  High Energy
Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate
University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  H.
Nakazawa  Department of Physics, National Taiwan University, Taipei 10617,
Taiwan  Z. Natkaniec  H. Niewodniczanski Institute of Nuclear Physics, Krakow
31-342, Poland  A. Natochii  University of Hawaii, Honolulu, Hawaii 96822,
U.S.A.  M. Nayak  Tel Aviv University, School of Physics and Astronomy, Tel
Aviv, 69978, Israel  G. Nazaryan  Alikhanyan National Science Laboratory,
Yerevan 0036, Armenia  D. Neverov  Graduate School of Science, Nagoya
University, Nagoya 464-8602, Japan  C. Niebuhr  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  M. Niiyama  Kyoto Sangyo
University, Kyoto 603-8555, Japan  J. Ninkovic  Semiconductor Laboratory of
the Max Planck Society, 81739 München, Germany  N. K. Nisar  Brookhaven
National Laboratory, Upton, New York 11973, U.S.A.  S. Nishida  High Energy
Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate
University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  K.
Nishimura  University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  M. Nishimura
High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
M. H. A. Nouxman  National Centre for Particle Physics, University Malaya,
50603 Kuala Lumpur, Malaysia  B. Oberhof  INFN Laboratori Nazionali di
Frascati, I-00044 Frascati, Italy  K. Ogawa  Niigata University, Niigata
950-2181, Japan  S. Ogawa  Toho University, Funabashi 274-8510, Japan  S. L.
Olsen  Gyeongsang National University, Jinju 52828, South Korea  Y. Onishchuk
Taras Shevchenko National Univ. of Kiev, Kiev, Ukraine  H. Ono  Niigata
University, Niigata 950-2181, Japan  Y. Onuki  Department of Physics,
University of Tokyo, Tokyo 113-0033, Japan  P. Oskin  P.N. Lebedev Physical
Institute of the Russian Academy of Sciences, Moscow 119991, Russian
Federation  E. R. Oxford  Carnegie Mellon University, Pittsburgh, Pennsylvania
15213, U.S.A.  H. Ozaki  High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan  The Graduate University for Advanced Studies
(SOKENDAI), Hayama 240-0193, Japan  P. Pakhlov  P.N. Lebedev Physical
Institute of the Russian Academy of Sciences, Moscow 119991, Russian
Federation  Moscow Physical Engineering Institute, Moscow 115409, Russian
Federation  G. Pakhlova  National Research University Higher School of
Economics, Moscow 101000, Russian Federation  P.N. Lebedev Physical Institute
of the Russian Academy of Sciences, Moscow 119991, Russian Federation  A.
Paladino  Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy
INFN Sezione di Pisa, I-56127 Pisa, Italy  T. Pang  University of Pittsburgh,
Pittsburgh, Pennsylvania 15260, U.S.A.  A. Panta  University of Mississippi,
University, Mississippi 38677, U.S.A.  E. Paoloni  Dipartimento di Fisica,
Università di Pisa, I-56127 Pisa, Italy  INFN Sezione di Pisa, I-56127 Pisa,
Italy  S. Pardi  INFN Sezione di Napoli, I-80126 Napoli, Italy  H. Park
Kyungpook National University, Daegu 41566, South Korea  S.-H. Park  High
Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  B.
Paschen  University of Bonn, 53115 Bonn, Germany  A. Passeri  INFN Sezione di
Roma Tre, I-00146 Roma, Italy  A. Pathak  University of Louisville,
Louisville, Kentucky 40292, U.S.A.  S. Patra  Indian Institute of Science
Education and Research Mohali, SAS Nagar, 140306, India  S. Paul  Department
of Physics, Technische Universität München, 85748 Garching, Germany  T. K.
Pedlar  Luther College, Decorah, Iowa 52101, U.S.A.  I. Peruzzi  INFN
Laboratori Nazionali di Frascati, I-00044 Frascati, Italy  R. Peschke
University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  R. Pestotnik  J. Stefan
Institute, 1000 Ljubljana, Slovenia  F. Pham  School of Physics, University of
Melbourne, Victoria 3010, Australia  M. Piccolo  INFN Laboratori Nazionali di
Frascati, I-00044 Frascati, Italy  L. E. Piilonen  Virginia Polytechnic
Institute and State University, Blacksburg, Virginia 24061, U.S.A.  G. Pinna
Angioni  Dipartimento di Fisica, Università di Torino, I-10125 Torino, Italy
INFN Sezione di Torino, I-10125 Torino, Italy  P. L. M. Podesta-Lerma
Universidad Autonoma de Sinaloa, Sinaloa 80000, Mexico  T. Podobnik  J. Stefan
Institute, 1000 Ljubljana, Slovenia  S. Pokharel  University of Mississippi,
University, Mississippi 38677, U.S.A.  G. Polat  Aix Marseille Université,
CNRS/IN2P3, CPPM, 13288 Marseille, France  V. Popov  National Research
University Higher School of Economics, Moscow 101000, Russian Federation  C.
Praz  Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  S. Prell  Iowa
State University, Ames, Iowa 50011, U.S.A.  E. Prencipe  Justus-Liebig-
Universität Gießen, 35392 Gießen, Germany  M. T. Prim  University of Bonn,
53115 Bonn, Germany  M. V. Purohit  Okinawa Institute of Science and
Technology, Okinawa 904-0495, Japan  H. Purwar  University of Hawaii,
Honolulu, Hawaii 96822, U.S.A.  N. Rad  Deutsches Elektronen–Synchrotron,
22607 Hamburg, Germany  P. Rados  Institute of High Energy Physics, Vienna
1050, Austria  S. Raiz  Dipartimento di Fisica, Università di Trieste, I-34127
Trieste, Italy  INFN Sezione di Trieste, I-34127 Trieste, Italy  R. Rasheed
Université de Strasbourg, CNRS, IPHC, UMR 7178, 67037 Strasbourg, France  M.
Reif  Max-Planck-Institut für Physik, 80805 München, Germany  S. Reiter
Justus-Liebig-Universität Gießen, 35392 Gießen, Germany  M. Remnev  Budker
Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation
Novosibirsk State University, Novosibirsk 630090, Russian Federation  P. K.
Resmi  Indian Institute of Technology Madras, Chennai 600036, India  I. Ripp-
Baudot  Université de Strasbourg, CNRS, IPHC, UMR 7178, 67037 Strasbourg,
France  M. Ritter  Ludwig Maximilians University, 80539 Munich, Germany  M.
Ritzert  University of Heidelberg, 68131 Mannheim, Germany  G. Rizzo
Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy  INFN Sezione
di Pisa, I-56127 Pisa, Italy  L. B. Rizzuto  J. Stefan Institute, 1000
Ljubljana, Slovenia  S. H. Robertson  McGill University, Montréal, Québec, H3A
2T8, Canada  Institute of Particle Physics (Canada), Victoria, British
Columbia V8W 2Y2, Canada  D. Rodríguez Pérez  Universidad Autonoma de Sinaloa,
Sinaloa 80000, Mexico  J. M. Roney  University of Victoria, Victoria, British
Columbia, V8W 3P6, Canada  Institute of Particle Physics (Canada), Victoria,
British Columbia V8W 2Y2, Canada  C. Rosenfeld  University of South Carolina,
Columbia, South Carolina 29208, U.S.A.  A. Rostomyan  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  N. Rout  Indian Institute of
Technology Madras, Chennai 600036, India  M. Rozanska  H. Niewodniczanski
Institute of Nuclear Physics, Krakow 31-342, Poland  G. Russo  Dipartimento di
Scienze Fisiche, Università di Napoli Federico II, I-80126 Napoli, Italy  INFN
Sezione di Napoli, I-80126 Napoli, Italy  D. Sahoo  Iowa State University,
Ames, Iowa 50011, U.S.A.  Y. Sakai  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University for
Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  D. A. Sanders  University
of Mississippi, University, Mississippi 38677, U.S.A.  S. Sandilya  Indian
Institute of Technology Hyderabad, Telangana 502285, India  A. Sangal
University of Cincinnati, Cincinnati, Ohio 45221, U.S.A.  L. Santelj  Faculty
of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
J. Stefan Institute, 1000 Ljubljana, Slovenia  P. Sartori  Dipartimento di
Fisica e Astronomia, Università di Padova, I-35131 Padova, Italy  INFN Sezione
di Padova, I-35131 Padova, Italy  Y. Sato  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  V. Savinov  University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, U.S.A.  B. Scavino  Institut für
Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany  M.
Schram  Pacific Northwest National Laboratory, Richland, Washington 99352,
U.S.A.  H. Schreeck  II. Physikalisches Institut, Georg-August-Universität
Göttingen, 37073 Göttingen, Germany  J. Schueler  University of Hawaii,
Honolulu, Hawaii 96822, U.S.A.  C. Schwanda  Institute of High Energy Physics,
Vienna 1050, Austria  A. J. Schwartz  University of Cincinnati, Cincinnati,
Ohio 45221, U.S.A.  B. Schwenker  II. Physikalisches Institut, Georg-August-
Universität Göttingen, 37073 Göttingen, Germany  R. M. Seddon  McGill
University, Montréal, Québec, H3A 2T8, Canada  Y. Seino  Niigata University,
Niigata 950-2181, Japan  A. Selce  INFN Sezione di Roma Tre, I-00146 Roma,
Italy  ENEA Casaccia, I-00123 Roma, Italy  K. Senyo  Yamagata University,
Yamagata 990-8560, Japan  I. S. Seong  University of Hawaii, Honolulu, Hawaii
96822, U.S.A.  J. Serrano  Aix Marseille Université, CNRS/IN2P3, CPPM, 13288
Marseille, France  M. E. Sevior  School of Physics, University of Melbourne,
Victoria 3010, Australia  C. Sfienti  Institut für Kernphysik, Johannes
Gutenberg-Universität Mainz, D-55099 Mainz, Germany  V. Shebalin  University
of Hawaii, Honolulu, Hawaii 96822, U.S.A.  C. P. Shen  Beihang University,
Beijing 100191, China  H. Shibuya  Toho University, Funabashi 274-8510, Japan
J.-G. Shiu  Department of Physics, National Taiwan University, Taipei 10617,
Taiwan  B. Shwartz  Budker Institute of Nuclear Physics SB RAS, Novosibirsk
630090, Russian Federation  Novosibirsk State University, Novosibirsk 630090,
Russian Federation  A. Sibidanov  University of Hawaii, Honolulu, Hawaii
96822, U.S.A.  F. Simon  Max-Planck-Institut für Physik, 80805 München,
Germany  J. B. Singh  Panjab University, Chandigarh 160014, India  S.
Skambraks  Institut für Experimentelle Teilchenphysik, Karlsruher Institut für
Technologie, 76131 Karlsruhe, Germany  K. Smith  School of Physics, University
of Melbourne, Victoria 3010, Australia  R. J. Sobie  University of Victoria,
Victoria, British Columbia, V8W 3P6, Canada  Institute of Particle Physics
(Canada), Victoria, British Columbia V8W 2Y2, Canada  A. Soffer  Tel Aviv
University, School of Physics and Astronomy, Tel Aviv, 69978, Israel  A.
Sokolov  Institute for High Energy Physics, Protvino 142281, Russian
Federation  Y. Soloviev  Deutsches Elektronen–Synchrotron, 22607 Hamburg,
Germany  E. Solovieva  P.N. Lebedev Physical Institute of the Russian Academy
of Sciences, Moscow 119991, Russian Federation  S. Spataro  Dipartimento di
Fisica, Università di Torino, I-10125 Torino, Italy  INFN Sezione di Torino,
I-10125 Torino, Italy  B. Spruck  Institut für Kernphysik, Johannes Gutenberg-
Universität Mainz, D-55099 Mainz, Germany  M. Starič  J. Stefan Institute,
1000 Ljubljana, Slovenia  S. Stefkova  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  Z. S. Stottler  Virginia Polytechnic Institute and State
University, Blacksburg, Virginia 24061, U.S.A.  R. Stroili  Dipartimento di
Fisica e Astronomia, Università di Padova, I-35131 Padova, Italy  INFN Sezione
di Padova, I-35131 Padova, Italy  J. Strube  Pacific Northwest National
Laboratory, Richland, Washington 99352, U.S.A.  J. Stypula  H. Niewodniczanski
Institute of Nuclear Physics, Krakow 31-342, Poland  R. Sugiura  Department of
Physics, University of Tokyo, Tokyo 113-0033, Japan  M. Sumihama  Gifu
University, Gifu 501-1193, Japan  Research Center for Nuclear Physics, Osaka
University, Osaka 567-0047, Japan  K. Sumisawa  High Energy Accelerator
Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University
for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  T. Sumiyoshi  Tokyo
Metropolitan University, Tokyo 192-0397, Japan  D. J. Summers  University of
Mississippi, University, Mississippi 38677, U.S.A.  W. Sutcliffe  University
of Bonn, 53115 Bonn, Germany  K. Suzuki  Graduate School of Science, Nagoya
University, Nagoya 464-8602, Japan  S. Y. Suzuki  High Energy Accelerator
Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University
for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  H. Svidras  Deutsches
Elektronen–Synchrotron, 22607 Hamburg, Germany  M. Tabata  Chiba University,
Chiba 263-8522, Japan  M. Takahashi  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  M. Takizawa  Meson Science Laboratory, Cluster for
Pioneering Research, RIKEN, Saitama 351-0198, Japan  J-PARC Branch, KEK Theory
Center, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801,
Japan  Showa Pharmaceutical University, Tokyo 194-8543, Japan  U. Tamponi
INFN Sezione di Torino, I-10125 Torino, Italy  S. Tanaka  High Energy
Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate
University for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  K. Tanida
Advanced Science Research Center, Japan Atomic Energy Agency, Naka 319-1195,
Japan  H. Tanigawa  Department of Physics, University of Tokyo, Tokyo
113-0033, Japan  N. Taniguchi  High Energy Accelerator Research Organization
(KEK), Tsukuba 305-0801, Japan  Y. Tao  University of Florida, Gainesville,
Florida 32611, U.S.A.  P. Taras  Université de Montréal, Physique des
Particules, Montréal, Québec, H3C 3J7, Canada  F. Tenchini  Dipartimento di
Fisica, Università di Pisa, I-56127 Pisa, Italy  INFN Sezione di Pisa, I-56127
Pisa, Italy  R. Tiwary  Tata Institute of Fundamental Research, Mumbai 400005,
India  D. Tonelli  INFN Sezione di Trieste, I-34127 Trieste, Italy  E. Torassa
INFN Sezione di Padova, I-35131 Padova, Italy  N. Toutounji  School of
Physics, University of Sydney, New South Wales 2006, Australia  K. Trabelsi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France  T. Tsuboyama
High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
The Graduate University for Advanced Studies (SOKENDAI), Hayama 240-0193,
Japan  N. Tsuzuki  Graduate School of Science, Nagoya University, Nagoya
464-8602, Japan  M. Uchida  Tokyo Institute of Technology, Tokyo 152-8550,
Japan  I. Ueda  High Energy Accelerator Research Organization (KEK), Tsukuba
305-0801, Japan  The Graduate University for Advanced Studies (SOKENDAI),
Hayama 240-0193, Japan  S. Uehara  High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University for
Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  Y. Uematsu  Department of
Physics, University of Tokyo, Tokyo 113-0033, Japan  T. Ueno  Department of
Physics, Tohoku University, Sendai 980-8578, Japan  T. Uglov  P.N. Lebedev
Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russian
Federation  National Research University Higher School of Economics, Moscow
101000, Russian Federation  K. Unger  Institut für Experimentelle
Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany
Y. Unno  Department of Physics and Institute of Natural Sciences, Hanyang
University, Seoul 04763, South Korea  K. Uno  Niigata University, Niigata
950-2181, Japan  S. Uno  High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan  The Graduate University for Advanced Studies
(SOKENDAI), Hayama 240-0193, Japan  P. Urquijo  School of Physics, University
of Melbourne, Victoria 3010, Australia  Y. Ushiroda  High Energy Accelerator
Research Organization (KEK), Tsukuba 305-0801, Japan  The Graduate University
for Advanced Studies (SOKENDAI), Hayama 240-0193, Japan  Department of
Physics, University of Tokyo, Tokyo 113-0033, Japan  Y. V. Usov  Budker
Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation
Novosibirsk State University, Novosibirsk 630090, Russian Federation  S. E.
Vahsen  University of Hawaii, Honolulu, Hawaii 96822, U.S.A.  R. van Tonder
University of Bonn, 53115 Bonn, Germany  G. S. Varner  University of Hawaii,
Honolulu, Hawaii 96822, U.S.A.  K. E. Varvell  School of Physics, University
of Sydney, New South Wales 2006, Australia  A. Vinokurova  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk
State University, Novosibirsk 630090, Russian Federation  L. Vitale
Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy  INFN
Sezione di Trieste, I-34127 Trieste, Italy  V. Vorobyev  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  P.N. Lebedev
Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russian
Federation  Novosibirsk State University, Novosibirsk 630090, Russian
Federation  A. Vossen  Duke University, Durham, North Carolina 27708, U.S.A.
B. Wach  Max-Planck-Institut für Physik, 80805 München, Germany  E. Waheed
High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
H. M. Wakeling  McGill University, Montréal, Québec, H3A 2T8, Canada  K. Wan
Department of Physics, University of Tokyo, Tokyo 113-0033, Japan  W. Wan
Abdullah  National Centre for Particle Physics, University Malaya, 50603 Kuala
Lumpur, Malaysia  B. Wang  Max-Planck-Institut für Physik, 80805 München,
Germany  C. H. Wang  National United University, Miao Li 36003, Taiwan  E.
Wang  University of Pittsburgh, Pittsburgh, Pennsylvania 15260, U.S.A.  M.-Z.
Wang  Department of Physics, National Taiwan University, Taipei 10617, Taiwan
X. L. Wang  Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)
and Institute of Modern Physics, Fudan University, Shanghai 200443, China  A.
Warburton  McGill University, Montréal, Québec, H3A 2T8, Canada  M. Watanabe
Niigata University, Niigata 950-2181, Japan  S. Watanuki  Yonsei University,
Seoul 03722, South Korea  J. Webb  School of Physics, University of Melbourne,
Victoria 3010, Australia  S. Wehle  Deutsches Elektronen–Synchrotron, 22607
Hamburg, Germany  M. Welsch  University of Bonn, 53115 Bonn, Germany  C.
Wessel  University of Bonn, 53115 Bonn, Germany  J. Wiechczynski  H.
Niewodniczanski Institute of Nuclear Physics, Krakow 31-342, Poland  P.
Wieduwilt  II. Physikalisches Institut, Georg-August-Universität Göttingen,
37073 Göttingen, Germany  H. Windel  Max-Planck-Institut für Physik, 80805
München, Germany  E. Won  Korea University, Seoul 02841, South Korea  L. J. Wu
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049,
China  X. P. Xu  Soochow University, Suzhou 215006, China  B. D. Yabsley
School of Physics, University of Sydney, New South Wales 2006, Australia  S.
Yamada  High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801,
Japan  W. Yan  University of Science and Technology of China, Hefei 230026,
China  S. B. Yang  Korea University, Seoul 02841, South Korea  H. Ye
Deutsches Elektronen–Synchrotron, 22607 Hamburg, Germany  J. Yelton
University of Florida, Gainesville, Florida 32611, U.S.A.  I. Yeo  Korea
Institute of Science and Technology Information, Daejeon 34141, South Korea
J. H. Yin  Korea University, Seoul 02841, South Korea  M. Yonenaga  Tokyo
Metropolitan University, Tokyo 192-0397, Japan  Y. M. Yook  Institute of High
Energy Physics, Chinese Academy of Sciences, Beijing 100049, China  K.
Yoshihara  Graduate School of Science, Nagoya University, Nagoya 464-8602,
Japan  T. Yoshinobu  Niigata University, Niigata 950-2181, Japan  C. Z. Yuan
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049,
China  G. Yuan  University of Science and Technology of China, Hefei 230026,
China  Y. Yusa  Niigata University, Niigata 950-2181, Japan  L. Zani  Aix
Marseille Université, CNRS/IN2P3, CPPM, 13288 Marseille, France  J. Z. Zhang
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049,
China  Y. Zhang  University of Science and Technology of China, Hefei 230026,
China  Z. Zhang  University of Science and Technology of China, Hefei 230026,
China  V. Zhilich  Budker Institute of Nuclear Physics SB RAS, Novosibirsk
630090, Russian Federation  Novosibirsk State University, Novosibirsk 630090,
Russian Federation  J. Zhou  Key Laboratory of Nuclear Physics and Ion-beam
Application (MOE) and Institute of Modern Physics, Fudan University, Shanghai
200443, China  Q. D. Zhou  Graduate School of Science, Nagoya University,
Nagoya 464-8602, Japan  Institute for Advanced Research, Nagoya University,
Nagoya 464-8602, Japan  Kobayashi-Maskawa Institute, Nagoya University, Nagoya
464-8602, Japan  X. Y. Zhou  Liaoning Normal University, Dalian 116029, China
V. I. Zhukova  P.N. Lebedev Physical Institute of the Russian Academy of
Sciences, Moscow 119991, Russian Federation  V. Zhulanov  Budker Institute of
Nuclear Physics SB RAS, Novosibirsk 630090, Russian Federation  Novosibirsk
State University, Novosibirsk 630090, Russian Federation

###### Abstract

We report a measurement of the branching fraction of the semileptonic decay
$B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ (and its charge
conjugate) using $62.8~{}\text{fb}^{-1}$ of $\mathchar
28935\relax(4S)\rightarrow B\bar{B}$ data recorded by the Belle II experiment
at the SuperKEKB asymmetric-energy $e^{+}e^{-}$ collider. The neutral charm
meson is searched for in the decay mode $D^{0}\rightarrow K^{-}\pi^{+}$ and
combined with a properly charged identified lepton (electron or muon) to
reconstruct this decay. No reconstruction of the second $B$ meson in the
$\mathchar 28935\relax(4S)$ event is performed. We obtain ${\cal
B}(B^{-}\rightarrow D^{0}\ell^{-}\bar{\nu}_{\ell})=(2.29\pm
0.05_{\mathrm{stat}}\pm 0.08_{\mathrm{syst}})\%$, in agreement with the world
average of this decay. We also determine the ratio of the electron to muon
branching fractions to be $R(e/\mu)=1.04\pm 0.05_{\mathrm{stat}}\pm
0.03_{\mathrm{syst}}$ and observe no deviation from lepton universality.

Belle II, $V_{cb}$

##  1 Introduction

The magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) Cabibbo (1963); Kobayashi
and Maskawa (1973) matrix element $|V_{cb}|$ squared determines the transition
rate of $b$\- into $c$-quarks and the precise knowledge of this fundamental
parameter of the Standard Model (SM) Pich (2008) is crucial for the ongoing
precision-$B$-physics programme at the Belle II experiment and elsewhere. The
CKM element $|V_{cb}|$ is measured from semileptonic $B$ meson decays
$B\rightarrow X_{c}\ell\nu$, where $X_{c}$ is a hadronic system with charm,
$\ell$ is a light charged lepton (electron or muon) and $\nu$ is the
associated neutrino. These determinations can be inclusive, i.e., sensitive to
all $X_{c}\ell\nu$ final states within a given region of phase space, or
exclusive, i.e., based only on a single $b\rightarrow c$ semileptonic mode
such as $B\rightarrow D^{*}\ell\nu$ or $B\rightarrow D\ell\nu$. Pursuing both
approaches is important as the two avenues involve different theoretical and
experimental uncertainties and consistency between both is a powerful cross-
check of our understanding. However, inclusive and exclusive measurements of
$|V_{cb}|$ are at odds for many years now, an issue which is often referred to
as the _inclusive vs. exclusive problem_ Amhis  _et al._ (2019).

In this paper we describe the measurement of the branching fraction of the
decay $B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ cc , a mode which
is expected to yield a precise determination of the CKM element $|V_{cb}|$
from the Belle II data. Neutral $D$ mesons are searched for in the decay mode
$D^{0}\rightarrow K^{-}\pi^{+}$ and combined with an identified lepton
(electron or muon) of the same charge as the kaon to reconstruct this decay.
To maximize the statistical power of the early Belle II data, this analysis is
untagged, i.e., we do not place any constraint on the second $B$ meson in the
$\mathchar 28935\relax(4S)$ event. The paper is organized as follows: Sect. 2
describes the real data and simulated data sets used throughout this analysis.
The experimental procedure is described in Sect. 3. Finally, Sect. 4 contains
the results of this analysis.

##  2 The Belle II detector and data sample

The Belle II detector Abe  _et al._ (2010); Kou  _et al._ (2019) operates at
the SuperKEKB asymmetric-energy electron-positron collider Akai  _et al._
(2018), located at the KEK laboratory in Tsukuba, Japan. The detector consists
of several nested detector subsystems arranged around the beam pipe in a
cylindrical geometry. The innermost subsystem is the vertex detector, which
includes two layers of silicon pixel detectors and four outer layers of
silicon strip detectors. Currently, the second pixel layer is installed in
only a small part of the solid angle, while the remaining vertex detector
layers are fully installed. Most of the tracking volume consists of a helium
and ethane-based small-cell drift chamber (CDC). Outside the drift chamber, a
Cherenkov-light imaging and time-of-propagation detector provides charged-
particle identification in the barrel region. In the forward endcap, this
function is provided by a proximity-focusing, ring-imaging Cherenkov detector
with an aerogel radiator. Further out is the ECL electromagnetic calorimeter,
consisting of a barrel and two endcap sections made of CsI(Tl) crystals. A
uniform 1.5 T magnetic field is provided by a superconducting solenoid
situated outside the calorimeter. Multiple layers of scintillators and
resistive plate chambers, located between the magnetic flux-return iron
plates, constitute the $K_{L}$ and muon identification system (KLM).

The data used in this analysis were collected in the years 2019 and 2020 at a
center-of-mass (c.m.) energy of 10.58 GeV, corresponding to the mass of the
$\mathchar 28935\relax$(4S) resonance. This data set corresponds to an
integrated luminosity of 62.8 fb-1 and contains $N_{B\bar{B}}=\left(68.21\pm
0.06_{\text{stat}}\pm 0.75_{\text{sys}}\right)\times 10^{6}$ $\mathchar
28935\relax(4S)\rightarrow B\bar{B}$ events as determined from a fit to event-
shape variables Abudinén  _et al._ .

Different samples of Monte Carlo (MC) simulated events are used throughout
this analysis. These include a sample of $\mathchar 28935\relax(4S)\rightarrow
B\bar{B}$ events in which $B$ mesons decay generically, generated with EvtGen
Lange (2001) and a sample of continuum $e^{+}e^{-}\rightarrow q\bar{q}$ events
($q=u,d,s,c$) simulated with KKMC Ward  _et al._ (2003), interfaced with
PYTHIA Sjostrand  _et al._ (2008). Full detector simulation based on GEANT4
Agostinelli  _et al._ (2003) is applied to MC events. The Monte Carlo samples
used in this analysis correspond to an integrated luminosity of 300 ${\rm
fb}^{-1}$. The lepton reconstruction efficiencies and the hadron
misidentification rates in simulation are adjusted to match the real
performance of the Belle II lepton identification system.

The data samples are processed using the Belle II software framework basf2
Kuhr  _et al._ (2019).

Prior to physics analysis, charged particle trajectories are reconstructed in
the vertex detector and the central drift chamber Bertacchi  _et al._ (2020).
Photons are reconstructed from ECL clusters unmatched to charged particle
tracks. Hadronic events are selected by requiring at least three charged
particles, a visible energy above 4 GeV, and a ratio $R_{2}$ of the second to
the zeroth Fox-Wolfram moments below 0.3 Fox and Wolfram (1978).

##  3 Experimental procedure

###  3.1 Reconstruction

We require charged particle tracks to originate from the interaction point
(IP): The distance of closest approach between each track and the interaction
point must be less than 2 cm along the $z$ direction (parallel to the beams)
and less than 0.5 cm in the transverse $r-\phi$ plane. We further require
charged particles to be within angular acceptance of the central drift chamber
and to have associated CDC hits.

Charged leptons (electron or muons) are required to have a c.m. momentum
greater than 0.6 GeV. Electrons are identified based on their energy and
shower shape in the ECL calorimeter. Muons are found based on the information
of the instrumented return yoke KLM. We attempt to recover bremsstahlung
photons radiated from an electron track by searching within a cone around the
lepton direction. If such photons, with an energy between 50 MeV and 150 MeV,
are found they are added to the electron candidate to correct the 4-momentum.

Neutral $D$ meson candidates are searched for in the decay mode to
$K^{-}\pi^{+}$, $D^{0}\rightarrow K^{-}\pi^{+}$. $D^{0}$ candidates are
accepted within a $K\pi$ invariant mass window from 1.857 GeV to 1.872 GeV.

Candidates for the decay $B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$
are obtained by combining an appropriately charged lepton with a neutral $D$
candidate. The mass of the $Y=D^{0}\ell$ system is required to exceed 3.15
GeV. For each $B$ candidate, we calculate the angle between the $Y$ and the
$B$ meson in the c.m. frame of the collision,

$\cos\theta_{BY}={2\,E_{B}^{*}E_{Y}^{*}-m_{B}^{2}-m_{Y}^{2}\over
2|p_{B}^{*}||p_{Y}^{*}|},$ (1)

where $E_{Y}^{*}$, $|p_{Y}^{*}|$, and $m_{Y}$ are the c.m. energy, momentum,
and invariant mass, respectively, of the $D^{0}\ell$ system, $m_{B}$ is the
nominal $B$ mass et al. and Group (2020), and $E_{B}^{*}$, $|p_{B}^{*}|$ are
the c.m. energy and momentum, respectively, of the $B$. The latter are
inferred from the beam 4-momenta. For correctly reconstructed
$B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ candidates, the value of
$\cos\theta_{BY}$ ranges within the interval $[-1,1]$. However, due to the
finite beam-energy spread, final-state radiation, and detector resolution, the
$\cos\theta_{BY}$ distributions of signal events are smeared beyond this
range. For background candidates, values outside of the $[-1,1]$ interval are
allowed. In the rest of the analysis, we retain $B$ candidates with a value of
$\cos\theta_{BY}$ ranging between $-4$ and 4.

To reduce the sizeable background of $B^{0}\rightarrow
D^{*-}(\bar{D}^{0}\pi^{-})\ell^{+}\nu_{\ell}$ and
$B^{+}\rightarrow\bar{D}^{*0}(\bar{D}^{0}\pi^{0})\ell^{+}\nu_{\ell}$ decays,
an active veto is applied. For $B^{0}\rightarrow
D^{*-}(\bar{D}^{0}\pi^{-})\ell^{+}\nu_{\ell}$, this is done by combining a
slow ($p<0.35$ GeV) pion of correct charge with the $D^{0}$ of a
$B^{+}\rightarrow\bar{D}^{0}\ell^{+}\nu_{\ell}$ candidate. If, for any slow
pion candidate in the event, the mass difference $\Delta M=M(D^{*})-M(D)$ is
found to be in the interval $[0.144,0.148]$ GeV, the $B^{+}$ candidate is
rejected. For
$B^{+}\rightarrow\bar{D}^{*0}(\bar{D}^{0}\pi^{0})\ell^{+}\nu_{\ell}$ decays,
we combine the $D^{0}$ with a neutral pion candidate and reject the
$B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ candidate, if $\Delta M$
is in the interval $[0.141,0.145]$ GeV and the opening angle between $D^{0}$
and $\pi^{0}$ is below 17 degrees. We reconstruct neutral pions from
$\pi^{0}\rightarrow\gamma\gamma$ and require different energies of the photon
daughters depending on the region of the detector the photon signature
originated from. We require $E>0.080$ GeV for the forward end-cap, $E>0.030$
GeV for the barrel region and $E>0.060$ GeV for the backward end-cap. The
$\pi^{0}$ mass is required to be in the interval $[0.120,0.145]$ GeV.

Fig. 1 shows the $\cos\theta_{BY}$ distributions of $B^{-}\rightarrow
D^{0}e^{-}\overline{\nu}_{e}$ and $B^{-}\rightarrow
D^{0}\mu^{-}\overline{\nu}_{\mu}$ candidates after applying the selections
described in this section.

Figure 1: $\cos\theta_{BY}$ distributions for selected $B^{-}\rightarrow
D^{0}e^{-}\overline{\nu}_{e}$ (left) and $B^{-}\rightarrow
D^{0}\mu^{-}\overline{\nu}_{\mu}$ candidates (right). The stacked histograms
are MC simulated events scaled to the real data luminosity of 62.8 fb-1. The
real data is shown by points with error bars.

###  3.2 Signal extraction

To extract the amount of signal in the selected sample, we perform separate
fits to the $\cos\theta_{BY}$ distributions of $B^{-}\rightarrow
D^{0}e^{-}\overline{\nu}_{e}$ and $B^{-}\rightarrow
D^{0}\mu^{-}\overline{\nu}_{\mu}$ candidates. We use a maximum likelihood
technique using Poisson statistics of both real and MC simulated data Barlow
and Beeston (1993). The MC shape of the signal, $D^{*}$ downfeed, background
from $B\bar{B}$ events and continuum background distributions is kept, while
the respective normalizations are free parameters in both fits.

Figure 2: Result of the fit to the $B^{-}\rightarrow
D^{0}e^{-}\overline{\nu}_{e}$ (left) and $B^{-}\rightarrow
D^{0}\mu^{-}\overline{\nu}_{\mu}$ samples (right). The stacked histograms are
MC simulated events scaled to match the result of the fit. The real data is
shown by points with error bars.

The fit results are shown in Table 1. We find $19,543\pm 628$ ($18,869\pm
636$) events in the electron (muon) channel. In Fig. 2 the stacked MC
components are scaled according to the fit results and the collision data is
shown by points with error bars.

| Fitted Yields
---|---
Channel | Signal | $D^{*}$ | Other $B\overline{B}$ | Continuum
$B^{-}\rightarrow D^{0}e^{-}\overline{\nu}_{e}$ | $19543\pm 648$ | $65502\pm 960$ | $59233\pm 2450$ | $79697\pm 1970$
$B^{-}\rightarrow D^{0}\mu^{-}\overline{\nu}_{\mu}$ | $18869\pm 636$ | $67595\pm 843$ | $64899\pm 2101$ | $102308\pm 1808$
Table 1: The fitted yield for each MC component determined from a maximum
likelihood fit in $\cos\theta_{BY}$. The uncertainties are statistical only.

##  4 Results and systematic uncertainty

###  4.1 $B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ branching
fraction

The fit result quoted in the previous section can be converted into a
measurement of the $B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$
branching ratio by using

$N_{\mathrm{sig}}=2\times N_{B\bar{B}}\times f_{+-}\times{\cal
B}(B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell})\times{\cal
B}(D^{0}\rightarrow K^{-}\pi^{+})\times\epsilon~{},$ (2)

where $N_{B\bar{B}}$ is the number of $\mathchar 28935\relax(4S)$ events in
the sample, $f_{+-}$ is the $B^{+}$ production fraction at the $\mathchar
28935\relax(4S)$ et al. and Group (2020), ${\cal B}(D^{0}\rightarrow
K^{-}\pi^{+})$ is the $D^{0}$ subdecay branching fraction et al. and Group
(2020) and $\epsilon$ is the overall selection criteria efficiency of this
analysis as determined from MC simulation. The results obtained in the two
samples are collected in Table 2.

Channel | Efficiency [%] | Branching fraction [%]
---|---|---
$B^{-}\rightarrow D^{0}e^{-}\overline{\nu}_{e}$ | 30.12 | $2.34\pm 0.08$
$B^{-}\rightarrow D^{0}\mu^{-}\overline{\nu}_{\mu}$ | 30.36 | $2.24\pm 0.08$
Table 2: Branching fractions of $B^{-}\rightarrow
D^{0}\ell^{-}\overline{\nu}_{\ell}$ determined in the electron and muon
samples. The uncertainties are statistical only.

###  4.2 Systematic uncertainty

The relative systematic uncertainties affecting the $B^{-}\rightarrow
D^{0}\ell^{-}\overline{\nu}_{\ell}$ branching fraction measurement are listed
in Table 3. We assume no correlation among the individual sources of
uncertainty and sum them in quadrature to obtain the total systematic
uncertainty. The methods used for obtaining these uncertainties are detailed
below.

| Relative uncertainty [%]
---|---
Source | $B^{-}\rightarrow D^{0}e^{-}\overline{\nu}_{e}$ | $B^{-}\rightarrow D^{0}\mu^{-}\overline{\nu}_{\mu}$
$N_{B^{\pm}}$ | 1.61 | 1.61
${\cal B}(D^{0}\rightarrow K^{-}\pi^{+})$ | 0.78 | 0.78
Tracking | 2.07 | 2.07
Lepton identification | 1.41 | 2.38
MC efficiency (statistical) | 0.09 | 0.09
$D\ell\nu$ form factor | 0.15 | 0.15
$D^{*}\ell\nu$ form factor | 0.44 | 0.44
Continuum shape | 0.37 | 0.37
Sum | 3.14 | 3.68
Table 3: Relative systematic uncertainty on the measurement of the
$B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell}$ branching fraction in
the two samples.

To correct for mismodelling of the lepton-identification in the MC compared to
collision events, we apply momentum-and polar-angle-dependent corrections. In
independent studies of $J/\psi\rightarrow\ell^{+}\ell^{-}$ and
$K_{S}\rightarrow\pi^{+}\pi^{-}$ decays, correction factors are obtained for
the reconstruction efficiency of leptons, and the mis-identification of
hadrons as leptons. Due to limited sample size in the control samples, the
lepton-identification correction factors are associated with statistical and
systematic uncertainties. By resampling the correction factors with Gaussian
distributions, while accounting for systematic correlations, we generate 500
sets of correction values. The 500 sets are used to estimate the systematic
uncertainty on $N_{\mathrm{sig}}$ caused by lepton-identification.

The uncertainty on the branching fraction of the hadronic decay mode ${\cal
B}(D^{0}\rightarrow K^{-}\pi^{+})$ = $(3.950\pm 0.031)\%$ Zyla  _et al._
(2020) enters the result of the signal yield as a systematic uncertainty.

The number of charged $B^{\pm}$ mesons in the data sample is calculated as

$N_{B^{\pm}}=2\times N_{B\bar{B}}\times f_{+-}~{}\,$ (3)

with $N_{B\bar{B}}=\left(68.21\pm 0.06_{\text{stat}}\pm
0.75_{\text{sys}}\right)\times 10^{6}$ and

$f_{+-}=\frac{\Gamma\left(\mathchar 28935\relax\left(4S\right)\rightarrow
B^{+}B^{-}\right)}{\Gamma\left(\mathchar
28935\relax\left(4S\right)\right)_{\mathrm{tot}}}=0.514\pm 0.006.$ (4)

The uncertainties on $f_{+-}$ and $N_{B\bar{B}}$ are added in quadrature to
estimate the impact on the measured branching fraction.

We account for the effect of finite MC sample sizes on the selection
efficiency $\epsilon$ with the binomial standard error.

A $e^{+}e^{-}\rightarrow\tau^{+}\tau^{-}$ performance study measures
discrepancies in the track finding efficiency between MC and collision data.
In accordance with the performance study, a relative systematic uncertainty of
$0.69~{}\%$ is assigned for each of the three charged final state tracks to
account for the track efficiency discrepancy.

The form factors describe the dependency of the decay rate on the kinematic
variable $w=v_{B}\cdot v_{D^{(*)}}$. The form factors impact on the shape of
signal and $D^{*}$ components has to be taken into account. We separately vary
the form factor parameters of the decays $B^{-}\rightarrow
D^{0}\ell^{-}\overline{\nu}_{\ell}$ and $\kern
1.79993pt\overline{\kern-1.79993ptB}{}^{0}\rightarrow
D^{*+}\ell^{-}\overline{\nu}_{\ell}$ in the parameterization of Caprini,
Lellouch and Neubert (CLN) Caprini  _et al._ (1998) by $1~{}\sigma$ around
their central values Amhis  _et al._ (2021) to estimate the corresponding
systematic uncertainty. The form factor uncertainty quoted in Table 3
corresponds to the quadratic sum of these individual variations.

Finally, the discrepancies between data and MC in the sidebands of the pre-fit
$\cos\theta_{BY}$ distributions in Fig. 1 are partly explained by mismodelling
of the continuum MC. We estimate the effect of this mismodelling on the
measured branching fractions by reweighing the continuum MC using collision
data recorded below the $\mathchar 28935\relax(4S)$.

##  5 Summary

We have measured the branching fraction of the decay $B^{-}\rightarrow
D^{0}\ell^{-}\overline{\nu}_{\ell}$ in 62.8 fb-1 of Belle II data. The results
in the electron and muon samples are

$\displaystyle{\cal B}(B^{-}\rightarrow D^{0}e^{-}\overline{\nu}_{e})$
$\displaystyle=$ $\displaystyle(2.34\pm 0.08_{\mathrm{stat}}\pm
0.07_{\mathrm{syst}})\%~{},$ (5) $\displaystyle{\cal B}(B^{-}\rightarrow
D^{0}\mu^{-}\overline{\nu}_{\mu})$ $\displaystyle=$ $\displaystyle(2.24\pm
0.08_{\mathrm{stat}}\pm 0.08_{\mathrm{syst}})\%~{},$ (6)

where the first error is statistical and the second systematic.

The weighted mean of both modes yields to this combined value of the branching
fraction

${\cal B}(B^{-}\rightarrow D^{0}\ell^{-}\overline{\nu}_{\ell})=(2.29\pm
0.05_{\mathrm{stat}}\pm 0.08_{\mathrm{syst}})\%~{},$ (7)

in agreement with the world average value of $(2.35\pm 0.03_{\mathrm{stat}}\pm
0.09_{\mathrm{syst}})\%$ Amhis  _et al._ (2021). For the ratio between the $e$
and $\mu$ channels, the uncertainties related to $N_{B^{\pm}}$ and ${\cal
B}(D^{0}\rightarrow K^{-}\pi^{+})$ cancel and we obtain

$R(e/\mu)=\frac{{\cal B}(B^{-}\rightarrow D^{0}e^{-}\overline{\nu}_{e})}{{\cal
B}(B^{-}\rightarrow D^{0}\mu^{-}\overline{\nu}_{\mu})}=1.04\pm
0.05_{\mathrm{stat}}\pm 0.03_{\mathrm{syst}}~{}.$ (8)

##  6 Acknowledgments

We thank the SuperKEKB group for the excellent operation of the accelerator;
the KEK cryogenics group for the efficient operation of the solenoid; the KEK
computer group for on-site computing support; and the raw-data centers at BNL,
DESY, GridKa, IN2P3, and INFN for off-site computing support. This work was
supported by the following funding sources: Science Committee of the Republic
of Armenia Grant No. 20TTCG-1C010; Australian Research Council and research
grant Nos. DP180102629, DP170102389, DP170102204, DP150103061, FT130100303,
FT130100018, and FT120100745; Austrian Federal Ministry of Education, Science
and Research, Austrian Science Fund No. P 31361-N36, and Horizon 2020 ERC
Starting Grant no. 947006 “InterLeptons”; Natural Sciences and Engineering
Research Council of Canada, Compute Canada and CANARIE; Chinese Academy of
Sciences and research grant No. QYZDJ-SSW-SLH011, National Natural Science
Foundation of China and research grant Nos. 11521505, 11575017, 11675166,
11761141009, 11705209, and 11975076, LiaoNing Revitalization Talents Program
under contract No. XLYC1807135, Shanghai Municipal Science and Technology
Committee under contract No. 19ZR1403000, Shanghai Pujiang Program under Grant
No. 18PJ1401000, and the CAS Center for Excellence in Particle Physics
(CCEPP); the Ministry of Education, Youth and Sports of the Czech Republic
under Contract No. LTT17020 and Charles University grants SVV 260448 and GAUK
404316; European Research Council, 7th Framework PIEF-GA-2013-622527, Horizon
2020 ERC-Advanced Grants No. 267104 and 884719, Horizon 2020 ERC-Consolidator
Grant No. 819127, Horizon 2020 Marie Sklodowska-Curie grant agreement No.
700525 ‘NIOBE,’ and Horizon 2020 Marie Sklodowska-Curie RISE project JENNIFER2
grant agreement No. 822070 (European grants); L’Institut National de Physique
Nucléaire et de Physique des Particules (IN2P3) du CNRS (France); BMBF, DFG,
HGF, MPG, and AvH Foundation (Germany); Department of Atomic Energy under
Project Identification No. RTI 4002 and Department of Science and Technology
(India); Israel Science Foundation grant No. 2476/17, United States-Israel
Binational Science Foundation grant No. 2016113, and Israel Ministry of
Science grant No. 3-16543; Istituto Nazionale di Fisica Nucleare and the
research grants BELLE2; Japan Society for the Promotion of Science, Grant-in-
Aid for Scientific Research grant Nos. 16H03968, 16H03993, 16H06492, 16K05323,
17H01133, 17H05405, 18K03621, 18H03710, 18H05226, 19H00682, 26220706, and
26400255, the National Institute of Informatics, and Science Information
NETwork 5 (SINET5), and the Ministry of Education, Culture, Sports, Science,
and Technology (MEXT) of Japan; National Research Foundation (NRF) of Korea
Grant Nos. 2016R1D1A1B01010135, 2016R1D1A1B02012900, 2018R1A2B3003643,
2018R1A6A1A06024970, 2018R1D1A1B07047294, 2019K1A3A7A09033840, and
2019R1I1A3A01058933, Radiation Science Research Institute, Foreign Large-size
Research Facility Application Supporting project, the Global Science
Experimental Data Hub Center of the Korea Institute of Science and Technology
Information and KREONET/GLORIAD; Universiti Malaya RU grant, Akademi Sains
Malaysia and Ministry of Education Malaysia; Frontiers of Science Program
contracts FOINS-296, CB-221329, CB-236394, CB-254409, and CB-180023, and SEP-
CINVESTAV research grant 237 (Mexico); the Polish Ministry of Science and
Higher Education and the National Science Center; the Ministry of Science and
Higher Education of the Russian Federation, Agreement 14.W03.31.0026, and the
HSE University Basic Research Program, Moscow; University of Tabuk research
grants S-0256-1438 and S-0280-1439 (Saudi Arabia); Slovenian Research Agency
and research grant Nos. J1-9124 and P1-0135; Agencia Estatal de Investigacion,
Spain grant Nos. FPA2014-55613-P and FPA2017-84445-P, and CIDEGENT/2018/020 of
Generalitat Valenciana; Ministry of Science and Technology and research grant
Nos. MOST106-2112-M-002-005-MY3 and MOST107-2119-M-002-035-MY3, and the
Ministry of Education (Taiwan); Thailand Center of Excellence in Physics;
TUBITAK ULAKBIM (Turkey); National Research Foundation of Ukraine, project No.
2020.02/0257, and Ministry of Education and Science of Ukraine; the US
National Science Foundation and research grant Nos. PHY-1807007 and
PHY-1913789, and the US Department of Energy and research grant Nos. DE-
AC06-76RLO1830, DE-SC0007983, DE-SC0009824, DE-SC0009973, DE-SC0010073, DE-
SC0010118, DE-SC0010504, DE-SC0011784, DE-SC0012704, DE-SC0021274; and the
Vietnam Academy of Science and Technology (VAST) under grant DL0000.05/21-23.

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