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Evidence for Top Quark Production in Nucleus-Nucleus Collisions

CMS Collaboration; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Frühwirth, R.; Jeitler, M.; Krammer, N.; Lechner, L.; Liko, D.; Madlener, T.; Mikulec, I.; Rad, N.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Templ, S.; ... mehr

Abstract:
Ultrarelativistic heavy ion collisions recreate in the laboratory the thermodynamical conditions prevailing in the early universe up to 10$^{Zahl}$  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$_{tt̅}$) 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$_{tt̅}$=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.


Verlagsausgabe §
DOI: 10.5445/IR/1000127766
Veröffentlicht am 17.12.2020
Originalveröffentlichung
DOI: 10.1103/PhysRevLett.125.222001
Scopus
Zitationen: 2
Dimensions
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Experimentelle Teilchenphysik (ETP)
Institut für Prozessdatenverarbeitung und Elektronik (IPE)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 0031-9007, 1079-7114
KITopen-ID: 1000127766
Erschienen in Physical review letters
Verlag American Physical Society (APS)
Band 125
Heft 22
Seiten Art.-Nr. 222001
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Vorab online veröffentlicht am 24.11.2020
Nachgewiesen in arXiv
Scopus
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