https://doi.org/10.1140/epjc/s10052-023-12104-7
Regular Article - Experimental Physics
Search for pair production of third-generation leptoquarks decaying into a bottom quark and a 
-lepton with the ATLAS detector
1
Department of Physics, University of Adelaide, Adelaide, Australia
2
Department of Physics, University of Alberta, Edmonton, AB, Canada
3
Department of Physics, Ankara University, Ankara, Türkiye
4
Division of Physics, TOBB University of Economics and Technology, Ankara, Türkiye
5
LAPP, Université Savoie Mont Blanc, CNRS/IN2P3, Annecy, France
6
APC, Université Paris Cité, CNRS/IN2P3, Paris, France
7
High Energy Physics Division, Argonne National Laboratory, Argonne, IL, USA
8
Department of Physics, University of Arizona, Tucson, AZ, USA
9
Department of Physics, University of Texas at Arlington, Arlington, TX, USA
10
Physics Department, National and Kapodistrian University of Athens, Athens, Greece
11
Physics Department, National Technical University of Athens, Zografou, Greece
12
Department of Physics, University of Texas at Austin, Austin, TX, USA
13
Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan
14
Institut de Física d’Altes Energies (IFAE), Barcelona Institute of Science and Technology, Barcelona, Spain
15
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
16
Physics Department, Tsinghua University, Beijing, China
17
Department of Physics, Nanjing University, Nanjing, China
18
University of Chinese Academy of Science (UCAS), Beijing, China
19
Institute of Physics, University of Belgrade, Belgrade, Serbia
20
Department for Physics and Technology, University of Bergen, Bergen, Norway
21
Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
22
University of California, Berkeley, CA, USA
23
Institut für Physik, Humboldt Universität zu Berlin, Berlin, Germany
24
Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics, University of Bern, Bern, Switzerland
25
School of Physics and Astronomy, University of Birmingham, Birmingham, UK
26
Department of Physics, Bogazici University, Istanbul, Türkiye
27
Department of Physics Engineering, Gaziantep University, Gaziantep, Türkiye
28
Department of Physics, Istanbul University, Istanbul, Türkiye
29
Istinye University, Sariyer, Istanbul, Türkiye
30
Facultad de Ciencias y Centro de Investigaciónes, Universidad Antonio Nariño, Bogotá, Colombia
31
Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
32
Dipartimento di Fisica e Astronomia A. Righi, Università di Bologna, Bologna, Italy
33
INFN Sezione di Bologna, Bologna, Italy
34
Physikalisches Institut, Universität Bonn, Bonn, Germany
35
Department of Physics, Boston University, Boston, MA, USA
36
Department of Physics, Brandeis University, Waltham, MA, USA
37
Transilvania University of Brasov, Brasov, Romania
38
Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania
39
Department of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, Romania
40
National Institute for Research and Development of Isotopic and Molecular Technologies, Physics Department, Cluj-Napoca, Romania
41
University Politehnica Bucharest, Bucharest, Romania
42
West University in Timisoara, Timisoara, Romania
43
Faculty of Physics, University of Bucharest, Bucharest, Romania
44
Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovak Republic
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Department of Subnuclear Physics, Institute of Experimental Physics of the Slovak Academy of Sciences, Kosice, Slovak Republic
46
Physics Department, Brookhaven National Laboratory, Upton, NY, USA
47
Departamento de Física, Facultad de Ciencias Exactas y Naturales, y CONICET, Instituto de Física de Buenos Aires (IFIBA), Universidad de Buenos Aires, Buenos Aires, Argentina
48
California State University, Fresno, CA, USA
49
Cavendish Laboratory, University of Cambridge, Cambridge, UK
50
Department of Physics, University of Cape Town, Cape Town, South Africa
51
iThemba Labs, Western Cape, South Africa
52
Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa
53
National Institute of Physics, University of the Philippines Diliman (Philippines), Philippines
54
University of South Africa, Department of Physics, Pretoria, South Africa
55
University of Zululand, KwaDlangezwa, South Africa
56
School of Physics, University of the Witwatersrand, Johannesburg, South Africa
57
Department of Physics, Carleton University, Ottawa, ON, Canada
58
Faculté des Sciences Ain Chock, Réseau Universitaire de Physique des Hautes Energies-Université Hassan II, Casablanca, Morocco
59
Faculté des Sciences, Université Ibn-Tofail, Kénitra, Morocco
60
Faculté des Sciences Semlalia, LPHEA-Marrakech, Université Cadi Ayyad, Marrakech, Morocco
61
LPMR, Faculté des Sciences, Université Mohamed Premier, Oujda, Morocco
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Faculté des sciences, Université Mohammed V, Rabat, Morocco
63
Institute of Applied Physics, Mohammed VI Polytechnic University, Ben Guerir, Morocco
64
CERN, Geneva, Switzerland
65
Affiliated with an Institute Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
66
Affiliated with an International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
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Enrico Fermi Institute, University of Chicago, Chicago, IL, USA
68
LPC, CNRS/IN2P3, Université Clermont Auvergne, Clermont-Ferrand, France
69
Nevis Laboratory, Columbia University, Irvington, NY, USA
70
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
71
Dipartimento di Fisica, Università della Calabria, Rende, Italy
72
Laboratori Nazionali di Frascati, INFN Gruppo Collegato di Cosenza, Cosenza, Italy
73
Physics Department, Southern Methodist University, Dallas, TX, USA
74
Physics Department, University of Texas at Dallas, Richardson, TX, USA
75
National Centre for Scientific Research “Demokritos”, Agia Paraskevi, Greece
76
Department of Physics, Stockholm University, Stockholm, Sweden
77
Oskar Klein Centre, Stockholm, Sweden
78
Deutsches Elektronen-Synchrotron DESY, Hamburg and Zeuthen, Germany
79
Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
80
Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
81
Department of Physics, Duke University, Durham, NC, USA
82
SUPA-School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
83
INFN e Laboratori Nazionali di Frascati, Frascati, Italy
84
Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
85
II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany
86
Département de Physique Nucléaire et Corpusculaire, Université de Genève, Geneva, Switzerland
87
Dipartimento di Fisica, Università di Genova, Genoa, Italy
88
INFN Sezione di Genova, Genoa, Italy
89
II. Physikalisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany
90
SUPA-School of Physics and Astronomy, University of Glasgow, Glasgow, UK
91
LPSC, CNRS/IN2P3, Grenoble INP, Université Grenoble Alpes, Grenoble, France
92
Laboratory for Particle Physics and Cosmology, Harvard University, Cambridge, MA, USA
93
Department of Modern Physics and State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, China
94
Institute of Frontier and Interdisciplinary Science and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Qingdao, China
95
School of Physics and Astronomy, Shanghai Jiao Tong University, Key Laboratory for Particle Astrophysics and Cosmology (MOE), SKLPPC, Shanghai, China
96
Tsung-Dao Lee Institute, Shanghai, China
97
Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
98
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
99
Department of Physics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
100
Department of Physics, University of Hong Kong, Hong Kong, China
101
Department of Physics and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
102
Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
103
IJCLab, CNRS/IN2P3, Université Paris-Saclay, 91405, Orsay, France
104
Centro Nacional de Microelectrónica (IMB-CNM-CSIC), Barcelona, Spain
105
Department of Physics, Indiana University, Bloomington, IN, USA
106
INFN Gruppo Collegato di Udine, Sezione di Trieste, Udine, Italy
107
ICTP, Trieste, Italy
108
Dipartimento Politecnico di Ingegneria e Architettura, Università di Udine, Udine, Italy
109
INFN Sezione di Lecce, Lecce, Italy
110
Dipartimento di Matematica e Fisica, Università del Salento, Lecce, Italy
111
INFN Sezione di Milano, Milan, Italy
112
Dipartimento di Fisica, Università di Milano, Milan, Italy
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INFN Sezione di Napoli, Naples, Italy
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Dipartimento di Fisica, Università di Napoli, Naples, Italy
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INFN Sezione di Pavia, Pavia, Italy
116
Dipartimento di Fisica, Università di Pavia, Pavia, Italy
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INFN Sezione di Pisa, Pisa, Italy
118
Dipartimento di Fisica E. Fermi, Università di Pisa, Pisa, Italy
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INFN Sezione di Roma, Rome, Italy
120
Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
121
INFN Sezione di Roma Tor Vergata, Rome, Italy
122
Dipartimento di Fisica, Università di Roma Tor Vergata, Rome, Italy
123
INFN Sezione di Roma Tre, Rome, Italy
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Dipartimento di Matematica e Fisica, Università Roma Tre, Rome, Italy
125
INFN-TIFPA, Povo, Italy
126
Università degli Studi di Trento, Trento, Italy
127
Universität Innsbruck, Department of Astro and Particle Physics, Innsbruck, Austria
128
University of Iowa, Iowa City, IA, USA
129
Department of Physics and Astronomy, Iowa State University, Ames, IA, USA
130
Departamento de Engenharia Elétrica, Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, Brazil
131
Universidade Federal do Rio De Janeiro COPPE/EE/IF, Rio de Janeiro, Brazil
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Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
133
Rio de Janeiro State University, Rio de Janeiro, Brazil
134
KEK, High Energy Accelerator Research Organization, Tsukuba, Japan
135
Graduate School of Science, Kobe University, Kobe, Japan
136
AGH University of Krakow, Faculty of Physics and Applied Computer Science, Kraków, Poland
137
Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
138
Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
139
Faculty of Science, Kyoto University, Kyoto, Japan
140
Kyoto University of Education, Kyoto, Japan
141
Research Center for Advanced Particle Physics and Department of Physics, Kyushu University, Fukuoka, Japan
142
Instituto de Física La Plata, Universidad Nacional de La Plata and CONICET, La Plata, Argentina
143
Physics Department, Lancaster University, Lancaster, UK
144
Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
145
Department of Experimental Particle Physics, Jožef Stefan Institute and Department of Physics, University of Ljubljana, Ljubljana, Slovenia
146
School of Physics and Astronomy, Queen Mary University of London, London, UK
147
Department of Physics, Royal Holloway University of London, Egham, UK
148
Department of Physics and Astronomy, University College London, London, UK
149
Louisiana Tech University, Ruston, LA, USA
150
Fysiska institutionen, Lunds universitet, Lund, Sweden
151
Departamento de Física Teorica C-15 and CIAFF, Universidad Autónoma de Madrid, Madrid, Spain
152
Institut für Physik, Universität Mainz, Mainz, Germany
153
School of Physics and Astronomy, University of Manchester, Manchester, UK
154
CPPM, CNRS/IN2P3, Aix-Marseille Université, Marseille, France
155
Department of Physics, University of Massachusetts, Amherst, MA, USA
156
Department of Physics, McGill University, Montreal, QC, Canada
157
School of Physics, University of Melbourne, Victoria, Australia
158
Department of Physics, University of Michigan, Ann Arbor, MI, USA
159
Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
160
Group of Particle Physics, University of Montreal, Montreal, QC, Canada
161
Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
162
Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Munich, Germany
163
Graduate School of Science and Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Japan
164
Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
165
Institute for Mathematics, Astrophysics and Particle Physics, Radboud University/Nikhef, Nijmegen, The Netherlands
166
Nikhef National Institute for Subatomic Physics and University of Amsterdam, Amsterdam, The Netherlands
167
Department of Physics, Northern Illinois University, DeKalb, IL, USA
168
New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
169
University of Sharjah, Sharjah, United Arab Emirates
170
Department of Physics, New York University, New York, NY, USA
171
Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo, Japan
172
Ohio State University, Columbus, OH, USA
173
Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, USA
174
Department of Physics, Oklahoma State University, Stillwater, OK, USA
175
Joint Laboratory of Optics, Palacký University, Olomouc, Czech Republic
176
Institute for Fundamental Science, University of Oregon, Eugene, OR, USA
177
Graduate School of Science, Osaka University, Osaka, Japan
178
Department of Physics, University of Oslo, Oslo, Norway
179
Department of Physics, Oxford University, Oxford, UK
180
LPNHE, CNRS/IN2P3, Sorbonne Université, Université Paris Cité, Paris, France
181
Department of Physics, University of Pennsylvania, Philadelphia, PA, USA
182
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA
183
Laboratório de Instrumentação e Física Experimental de Partículas-LIP, Lisbon, Portugal
184
Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
185
Departamento de Física, Universidade de Coimbra, Coimbra, Portugal
186
Centro de Física Nuclear da Universidade de Lisboa, Lisbon, Portugal
187
Departamento de Física, Universidade do Minho, Braga, Portugal
188
Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada (Spain), Portugal
189
Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
190
Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic
191
Czech Technical University in Prague, Prague, Czech Republic
192
Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
193
Particle Physics Department, Rutherford Appleton Laboratory, Didcot, UK
194
IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
195
Santa Cruz Institute for Particle Physics, University of California Santa Cruz, Santa Cruz, CA, USA
196
Departamento de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
197
Millennium Institute for Subatomic Physics at High Energy Frontier (SAPHIR), Santiago, Chile
198
Instituto de Investigación Multidisciplinario en Ciencia y Tecnología, y Departamento de Física, Universidad de La Serena, La Serena, Chile
199
Universidad Andres Bello, Department of Physics, Santiago, Chile
200
Instituto de Alta Investigación, Universidad de Tarapacá, Arica, Chile
201
Departamento de Física, Universidad Técnica Federico Santa María, Valparaíso, Chile
202
Department of Physics, University of Washington, Seattle, WA, USA
203
Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
204
Department of Physics, Shinshu University, Nagano, Japan
205
Department Physik, Universität Siegen, Siegen, Germany
206
Department of Physics, Simon Fraser University, Burnaby, BC, Canada
207
SLAC National Accelerator Laboratory, Stanford, CA, USA
208
Department of Physics, Royal Institute of Technology, Stockholm, Sweden
209
Departments of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA
210
Department of Physics and Astronomy, University of Sussex, Brighton, UK
211
School of Physics, University of Sydney, Sydney, Australia
212
Institute of Physics, Academia Sinica, Taipei, Taiwan
213
E. Andronikashvili Institute of Physics, Iv. Javakhishvili Tbilisi State University, Tbilisi, Georgia
214
High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia
215
University of Georgia, Tbilisi, Georgia
216
Department of Physics, Technion, Israel Institute of Technology, Haifa, Israel
217
Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
218
Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
219
International Center for Elementary Particle Physics and Department of Physics, University of Tokyo, Tokyo, Japan
220
Department of Physics, Tokyo Institute of Technology, Tokyo, Japan
221
Department of Physics, University of Toronto, Toronto, ON, Canada
222
TRIUMF, Vancouver, BC, Canada
223
Department of Physics and Astronomy, York University, Toronto, ON, Canada
224
Division of Physics and Tomonaga Center for the History of the Universe, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
225
Department of Physics and Astronomy, Tufts University, Medford, MA, USA
226
United Arab Emirates University, Al Ain, United Arab Emirates
227
Department of Physics and Astronomy, University of California Irvine, Irvine, CA, USA
228
Department of Physics and Astronomy, University of Uppsala, Uppsala, Sweden
229
Department of Physics, University of Illinois, Urbana, IL, USA
230
Instituto de Física Corpuscular (IFIC), Centro Mixto Universidad de Valencia-CSIC, Valencia, Spain
231
Department of Physics, University of British Columbia, Vancouver, BC, Canada
232
Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
233
Fakultät für Physik und Astronomie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
234
Department of Physics, University of Warwick, Coventry, UK
235
Waseda University, Tokyo, Japan
236
Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot, Israel
237
Department of Physics, University of Wisconsin, Madison, WI, USA
238
Fakultät für Mathematik und Naturwissenschaften, Fachgruppe Physik, Bergische Universität Wuppertal, Wuppertal, Germany
239
Department of Physics, Yale University, New Haven, CT, USA
240
Affiliated with an Institute Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
241
An-Najah National University, Nablus, Palestine
242
Borough of Manhattan Community College, City University of New York, New York, NY, USA
243
Bruno Kessler Foundation, Trento, Italy
244
Center for High Energy Physics, Peking University, Beijing, China
245
Also at Center for Interdisciplinary Research and Innovation (CIRI-AUTH), Thessaloniki, Greece
246
Centro Studi e Ricerche Enrico Fermi, Rome, Italy
247
CERN, Geneva, Switzerland
248
Département de Physique Nucléaire et Corpusculaire, Université de Genève, Geneva, Switzerland
249
Departament de Fisica de la Universitat Autonoma de Barcelona, Barcelona, Spain
250
Department of Financial and Management Engineering, University of the Aegean, Chios, Greece
251
Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
252
Department of Physics, Ben Gurion University of the Negev, Beer Sheva, Israel
253
Department of Physics, California State University, East Bay, USA
254
Department of Physics, California State University, Sacramento, USA
255
Department of Physics, King’s College London, London, UK
256
Department of Physics, Stanford University, Stanford, CA, USA
257
Department of Physics, University of Fribourg, Fribourg, Switzerland
258
Department of Physics, University of Thessaly, Volos, Greece
259
Department of Physics, Westmont College, Santa Barbara, USA
260
Hellenic Open University, Patras, Greece
261
Institucio Catalana de Recerca i Estudis Avancats, ICREA, Barcelona, Spain
262
Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany
263
Institute for Nuclear Research and Nuclear Energy (INRNE) of the Bulgarian Academy of Sciences, Sofia, Bulgaria
264
Institute of Applied Physics, Mohammed VI Polytechnic University, Ben Guerir, Morocco
265
Institute of Particle Physics (IPP), Victoria, Canada
266
Institute of Physics and Technology, Ulaanbaatar, Mongolia
267
Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan
268
Institute of Theoretical Physics, Ilia State University, Tbilisi, Georgia
269
L2IT, CNRS/IN2P3, UPS, Université de Toulouse, Toulouse, France
270
Lawrence Livermore National Laboratory, Livermore, USA
271
National Institute of Physics, University of the Philippines Diliman (Philippines), Quezon City, Philippines
272
Technical University of Munich, Munich, Germany
273
The Collaborative Innovation Center of Quantum Matter (CICQM), Beijing, China
274
TRIUMF, Vancouver, BC, Canada
275
Università di Napoli Parthenope, Naples, Italy
276
University of Chinese Academy of Sciences (UCAS), Beijing, China
277
University of Colorado Boulder, Department of Physics, Colorado, USA
278
Washington College, Maryland, USA
279
Yeditepe University, Physics Department, Istanbul, Türkiye
280
CERN, 1211, Geneva 23, Switzerland
Received:
3
March
2023
Accepted:
2
October
2023
Published online:
24
November
2023
A search for pair-produced scalar or vector leptoquarks decaying into a b-quark and a -lepton is presented using the full LHC Run 2 (2015–2018) data sample of 139 fb
collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of 
TeV. Events in which at least one -lepton decays hadronically are considered, and multivariate discriminants are used to extract the signals. No significant deviations from the Standard Model expectation are observed and 95% confidence-level upper limits on the production cross-section are derived as a function of leptoquark mass and branching ratio 
into a -lepton and b-quark. For scalar leptoquarks, masses below 1460 GeV are excluded assuming 
%, while for vector leptoquarks the corresponding limit is 1650 GeV (1910 GeV) in the minimal-coupling (Yang–Mills) scenario.
D. Brucnko, A. Budagov, E. F. Torregrosa, V. Gratchev, M. Lokajicek, J. Olszowska, L. Perini, S. Y. Sivollokov: Deceased.
© The Author(s) 2023
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