Observation of medium-induced modifications of Jet fragmentation in Pb-Pb collisions at sNN =5.02 TeV using isolated photon-tagged jets

Sirunyan, A. M. and Tumasyan, A. R. and Adam, Wolfgang and Ambrogi, Federico and Asilar, Ece and Md. Ali, Mohd. Adli (2018) Observation of medium-induced modifications of Jet fragmentation in Pb-Pb collisions at sNN =5.02 TeV using isolated photon-tagged jets. Physical Review Letters, 121 (24). pp. 1-18. ISSN 0031-9007 E-ISSN 1079-7114

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Abstract

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 pjet T > 30 GeV=c in events containing an isolated photon with pγ T > 60 GeV=c, using charged tracks with transverse momentum ptrk T > 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.

Item Type:	Article (Journal)
Additional Information:	7861/70737
Uncontrolled Keywords:	Medium-induced; modifications of jet fragmentation; Pb-Pb collisions; sNN p = 5.02; Isolated photon-tagged jets
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Science Kulliyyah of Science > Department of Physics
Depositing User:	Dr Mohd Adli MD Ali
Date Deposited:	14 Feb 2019 14:09
Last Modified:	15 Jul 2019 09:09
URI:	http://irep.iium.edu.my/id/eprint/70737

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