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



Adam, J, Adamova, D, Aggarwal, MM, Rinella, G Aglieri, Agnello, M, Agrawal, N, Ahammed, Z, Ahmad, S, Ahn, SU, Aiola, S
et al (show 1000 more authors) (2016) Jet-like correlations with neutral pion triggers in pp and central Pb-Pb collisions at 2.76 TeV. PHYSICS LETTERS B, 763. pp. 238-250.

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Abstract

We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pTtrig>16 GeV/c and associated charged particles of 0.5>pTassoc>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 pTassoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low pTassoc. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest pTassoc 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 pTassoc. Only AMPT captures the enhancement at low pTassoc, 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
Uncontrolled Keywords: 5106 Nuclear and Plasma Physics, 5107 Particle and High Energy Physics, 51 Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Mar 2017 11:08
Last Modified: 20 Jun 2024 19:07
DOI: 10.1016/j.physletb.2016.10.048
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3006436