Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at √sNN = 2.76 TeV

Adam, J. and Antičić, Tome and Erhardt, Filip and Planinić, Mirko and Poljak, Nikola and Simatović, Goran and Utrobičić, Antonija and Zyzak, M. (ALICE Collaboration) (2015) Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at √sNN = 2.76 TeV. Journal of High Energy Physics, 2015 (9). pp. 170-42. ISSN 1029-8479

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Abstract

We report the measurement of a new observable of jet quenching in central Pb-Pb collisions at √ sNN = 2.76 TeV, based on the semi-inclusive rate of charged jets recoiling from a high transverse momentum (high-pT) charged hadron trigger. Jets are measured using collinear-safe jet reconstruction with infrared cutoff for jet constituents of 0.15 GeV, for jet resolution parameters R = 0.2, 0.4 and 0.5. Underlying event background is corrected at the event-ensemble level, without imposing bias on the jet population. Recoil jet spectra are reported in the range 20 < pch T,jet < 100 GeV. Reference distributions for pp collisions at √ s = 2.76 TeV are calculated using Monte Carlo and NLO pQCD methods, which are validated by comparing with measurements in pp collisions at √ s = 7 TeV. The recoil jet yield in central Pb-Pb collisions is found to be suppressed relative to that in pp collisions. No significant medium-induced broadening of the intra-jet energy profile is observed within 0.5 radians relative to the recoil jet axis. The angular distribution of the recoil jet yield relative to the trigger axis is found to be similar in central Pb-Pb and pp collisions, with no significant medium-induced acoplanarity observed. Large-angle jet deflection, which may provide a direct probe of the nature of the quasi-particles in hot QCD matter, is explored.

Item Type: Article
Keywords: quark gluon plasma, jet physics, heavy ions
Date: September 2015
Subjects: NATURAL SCIENCES > Physics
Additional Information: Open Access. © Copyright CERN, for the benefit of the ALICE Collaboration. Article funded by SCOAP3. Received: June 24, 2015. Accepted: August 27, 2015. Published: September 24, 2015
Divisions: Faculty of Science > Department of Physics
Publisher: Springer
Depositing User: Nikola Poljak
Date Deposited: 27 May 2016 20:37
Last Modified: 28 May 2016 20:00
URI: http://digre.pmf.unizg.hr/id/eprint/4861

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