Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV

Adam, J. and Antičić, Tome and Erhardt, Filip and Gotovac, Sven and Mudnić, Eugen and Planinić, Mirko and Poljak, Nikola and Simatović, Goran and Utrobičić, Antonija and Vicković, Linda and Zmeskal, J. (ALICE Collaboration) (2016) Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV. Physics Letters B, 763. 238 - 250. ISSN 0370-2693

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We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8< ptrigT< 16 GeV/c and associated charged particles of 0.5< passocT< 10 GeV/c versus the azimuthal angle difference Δφ at midrapidity in pp and central Pb-Pb collisions at sNN−−−√=2.76 TeV with ALICE. The new measurements exploit associated charged hadrons down to 0.5 GeV/c, which significantly extends our previous measurement that only used charged hadrons above 3 GeV/c. After subtracting the contributions of the flow background, v2 to v5, the per-trigger yields are extracted for |Δφ|< 0.7 on the near and for |Δφ−π|< 1.1 on the away side. The ratio of per-trigger yields in Pb-Pb to those in pp collisions, IAA, is measured on the near and away side for the 0--10\% most central Pb-Pb collisions. On the away side, the per-trigger yields in Pb-Pb are strongly suppressed to the level of IAA≈0.6 for passocT>3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low passocT. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest passocT is observed. The data are compared to parton-energy-loss predictions of the JEWEL and AMPT event generators, as well as to a perturbative QCD calculation with medium-modified fragmentation functions. All calculations qualitatively describe the away-side suppression at high passocT. Only AMPT captures the enhancement at low passocT, both on the near and away side. However, it also underpredicts IAA above 5 GeV/c, in particular on the near-side.

Item Type: Article
Date: 10 December 2016
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2016 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license ( Funded by SCOAP3. Received 29 August 2016, Revised 10 October 2016, Accepted 18 October 2016, Available online 24 October 2016.
Divisions: Faculty of Science > Department of Physics
Publisher: Elsevier
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 01 Dec 2016 16:37
Last Modified: 01 May 2018 15:43

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