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

0472826 - ÚJF 2017 RIV NL eng J - Journal Article
Adam, J. - Adamová, Dagmar - Bielčík, J. - Bielčíková, Jana - Broz, M. - Čepila, J. - Contreras, J. G. - Eyyubova, G. - Ferencei, Jozef - Horák, D. - Křížek, Filip - Kučera, Vít - Mareš, Jiří A. - Petráček, V. - Pospíšil, Jan - Šumbera, Michal - Vaňát, Tomáš - Závada, Petr … Total 1010 authors
Jet-like correlations with neutral pion triggers in pp and central Pb–Pb collisions at 2.76 TeV.
Physics Letters. B. Roč. 763, DEC (2016), s. 238-250. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA MŠMT(CZ) LG13031
Institutional support: RVO:68378271 ; RVO:61389005
Keywords : ALICE collaboration * two-particle correlations * heavy ion collisions
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders; BF - Elementary Particles and High Energy Physics (FZU-D)
Impact factor: 4.807, year: 2016

We present measurements of two-particle correlations with neutral pion trigger particles of transverse momenta 8>pT trig>16 GeV/c and associated charged particles of 0.5>pT assoc>10 GeV/c versus the azimuthal angle difference delta phi at midrapidity in pp and central Pb–Pb collisions at root s-NN=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 delta phi>0.7 on the near and for delta phi - pi>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 approx.0.6 for pT assoc<3 GeV/c, while with decreasing momenta an enhancement develops reaching about 5 at low pT assoc. On the near side, an enhancement of IAA between 1.2 at the highest to 1.8 at the lowest pT assoc 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 pT assoc. Only AMPT captures the enhancement at low pT assoc, both on the near and away side. However, it also underpredicts IAA above 5 GeV/c, in particular on the near-side.
Permanent Link: http://hdl.handle.net/11104/0270047