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Observation of Medium-Induced Modifications of Jet Fragmentation in Pb-Pb Collisions at √$^{S}$NN = 5.02 TeV Using Isolated Photon-Tagged Jets

CMS Collaboration; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; ... mehr

Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and Pb-Pb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with pjetT>30  GeV/c in events containing an isolated photon with pγT>60  GeV/c, using charged tracks with transverse momentum ptrkT>1  GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial pT and azimuthal angle of the parton whose shower produced the jet. For central Pb-Pb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central Pb-Pb events show an excess (depletion) of low (high) pT particles, with a transition around 3  GeV/c. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well-defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the quark-gluon plasma.

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Verlagsausgabe §
DOI: 10.5445/IR/1000089150
Veröffentlicht am 07.01.2019
DOI: 10.1103/PhysRevLett.121.242301
Zitationen: 13
Web of Science
Zitationen: 7
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Experimentelle Kernphysik (IEKP)
Institut für Prozessdatenverarbeitung und Elektronik (IPE)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2018
Sprache Englisch
Identifikator ISSN: 0031-9007, 1079-7114
KITopen-ID: 1000089150
Erschienen in Physical review letters
Verlag American Physical Society (APS)
Band 121
Heft 24
Seiten Article: 242301
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Vorab online veröffentlicht am 14.12.2018
Nachgewiesen in Scopus
Web of Science
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