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Title
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Observation of medium-induced modifications of jet fragmentation in Pb-Pb collisions at =5.02 TeV using isolated photon-tagged jets
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Author
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Institution/Organisation
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CMS Collaboration
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Abstract
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| 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 P-T(jet) 30 GeV/c in events containing an isolated photon with p(T)(gamma) 60 GeV/c, using charged tracks with transverse momentum p(T)(trk) > 1 GeV/c in a cone around the jet axis. The association with an isolated photon constrains the initial p(T) 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) p(T) 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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Language
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English
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Source (journal)
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Physical review letters. - New York, N.Y., 1958, currens
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Publication
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New York, N.Y.
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American Physical Society
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2018
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ISSN
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0031-9007
[print]
1079-7114
[online]
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DOI
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10.1103/PHYSREVLETT.121.242301
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Volume/pages
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121
:24
(2018)
, 18 p.
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Article Reference
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242301
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ISI
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000453476900007
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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