Measurement of angular and momentum distributions of charged particles within and around jets in Pb + Pb and pp collisions at √sNN =5.02 TeV with the ATLAS detector

ATLAS Collaboration

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Abstract

Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in √sNN = 5.02 TeV Pb + Pb and pp collisions, using the ATLAS detector at the LHC. The Pb + Pb and pp data sets have integrated luminosities of 0.49 nb-1 and 25 pb-1, respectively. The measurement is performed for jets reconstructed with the anti-kt algorithm with radius parameter R = 0.4 and is extended to an angular distance of r = 0.8 from the jet axis. Results are presented as a function of Pb + Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1- to 63-GeV range, matched to jets with transverse momenta in the 126- to 316-GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in pp collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at r = 0.6. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb+Pb collisions in the jet core for angular distances up to r = 0.05 from the jet axis, with a suppression at larger distances.

Original languageEnglish
Article number064901
Pages (from-to)064901-1-064901-29
Number of pages29
JournalPhysical Review C
Volume100
Issue number6
DOIs
Publication statusPublished - Dec 2019
Externally publishedYes

Bibliographical note

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