Published November 27, 2020 | Version Submitted + Supplemental Material + Published
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Evidence for Top Quark Production in Nucleus-Nucleus Collisions

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Abstract

Ultrarelativistic heavy ion collisions recreate in the laboratory the thermodynamical conditions prevailing in the early universe up to 10⁻⁶  sec, thereby allowing the study of the quark-gluon plasma (QGP), a state of quantum chromodynamics (QCD) matter with deconfined partons. The top quark, the heaviest elementary particle known, is accessible in nucleus-nucleus collisions at the CERN LHC, and constitutes a novel probe of the QGP. Here, we report the first evidence for the production of top quarks in nucleus-nucleus collisions, using lead-lead collision data at a nucleon-nucleon center-of-mass energy of 5.02 TeV recorded by the CMS experiment. Two methods are used to measure the cross section for top quark pair production (σ_(tt̄)) via the selection of charged leptons (electrons or muons) and bottom quarks. One method relies on the leptonic information alone, and the second one exploits, in addition, the presence of bottom quarks. The measured cross sections, σ_(tt̄) = 2.54^(+0.84)_(−0.74) and 2.03^(+0.71)_(−0.64)  μb, respectively, are compatible with expectations from scaled proton-proton data and QCD predictions.

Additional Information

© 2020 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3. Received 28 July 2020; accepted 7 October 2020; published 24 November 2020. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centers and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMBWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, PUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); NKFIA (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR, and NRC KI (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI, and FEDER (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).

Attached Files

Published - PhysRevLett.125.222001.pdf

Submitted - 2006.11110.pdf

Supplemental Material - HIN-19-001_supp-jnl.pdf

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2006.11110.pdf

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Identifiers

Eprint ID
107246
Resolver ID
CaltechAUTHORS:20201222-070141250

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Funding

Bundesministerium für Wissenschaft, Forschung Und Wirtschaft (BMWFW)
FWF Der Wissenschaftsfond
Fonds de la Recherche Scientifique (FNRS)
Fonds Wetenschappelijk Onderzoek (FWO)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Ministry of Education and Science (Bulgaria)
CERN
Chinese Academy of Sciences
Ministry of Science and Technology (China)
National Natural Science Foundation of China
Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS)
Ministry of Science, Education and Sport (Croatia)
Croatian Science Foundation
Research Promotion Foundation (Cyprus)
Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovación (SENESCYT)
Ministry of Education and Research (Estonia)
Estonian Research Council
PUT (Estonia)
European Regional Development Fund (Estonia)
Academy of Finland
Ministry of Education and Culture (Finland)
Helsinki Institute of Physics
Commissariat a l'Energie Atomique (CEA)
Centre National de la Recherche Scientifique (CNRS)
Institut National de Physique Nucléaire et de Physique des Particules (IN2P3)
Bundesministerium für Bildung und Forschung (BMBF)
Deutsche Forschungsgemeinschaft (DFG)
Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF)
General Secretariat for Research and Technology (GSRT)
National Research, Development and Innovation Fund (NKFIA)
Department of Atomic Energy (India)
Department of Science and Technology (India)
Institute for Studies in Theoretical Physics and Mathematics (Iran)
Science Foundation, Ireland
Istituto Nazionale di Fisica Nucleare (INFN)
Ministry of Science, ICT and Future Planning (Korea)
National Research Foundation of Korea
Ministry of Education and Science (Latvia)
Lithuanian Academy of Sciences
Ministry of Education (Malaysia)
University of Malaya
Benemérita Universidad Autónoma de Puebla (BUAP)
Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV)
Consejo Nacional de Ciencia y Tecnología (CONACYT)
Laboratorio Nacional de Supercómputo (LNS)
Secretaría de Educación Pública (SEP)
Universidad Autónoma de San Luis Potosí Inicio-Facultad de Ingeniería (UASLP-FAI)
Ministero della Scienza del Montenegro (MOS)
Ministry of Business, Innovation and Employment (New Zealand)
Atomic Energy Commission (Pakistan)
Ministry of Science and Higher Education (Poland)
National Science Centre (Poland)
Fundação para a Ciência e Tecnologia (FCT)
Joint Institute for Nuclear Research (JINR)
RosAtom
Russian Academy of Sciences
Russian Foundation for Basic Research
National Research Center, Kurchatov Institute (Russia)
Ministry of Education, Science and Technological Development (Serbia)
Secretaría de Estado de Investigación, Desarrollo e Innovación (SEIDI)
Centro Nacional de Física de Partículas, Astropartículas y Nuclear (CPAN)
Plan de Ciencia, Tecnología e Innovació (PCTI)
Fondo Europeo de Desarrollo Regional (FEDER)
Ministry of Science, Technology and Research (Sri Lanka)
Swiss Funding Agencies
Ministry of Science and Technology (Taipei)
Thailand Center of Excellence in Physics
Institute for the Promotion of Teaching Science and Technology (Thailand)
Special Task Force for Activating Research (Thailand)
National Science and Technology Development Agency (Thailand)
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK)
Türkiye Atom Enerjisi Kurumu (TAEK)
National Academy of Sciences (Ukraine)
Science and Technology Facilities Council (STFC)
Department of Energy (DOE)
NSF
SCOAP3

Dates

Created
2020-12-23
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Updated
2023-03-16
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