Abstract
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 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 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.
Original language | English |
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Pages (from-to) | 238-250 |
Number of pages | 13 |
Journal | Physics Letters B |
Volume | 763 |
DOIs | |
State | Published - Dec 10 2016 |
Funding
The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable contributions to the construction of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources and support provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration. The ALICE Collaboration acknowledges the following funding agencies for their support in building and running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation (ANSL) , State Committee of Science and World Federation of Scientists (WFS), Armenia ; Austrian Academy of Sciences and Österreichische Nationalstiftung für Forschung, Technologie und Entwicklung, Austria ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) , Financiadora de Estudos e Projetos (Finep) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Brazil ; Ministry of Education of China (MOE of China) , Ministry of Science & Technology of China (MOST of China) and National Natural Science Foundation of China (NSFC), China ; Ministry of Science, Education and Sport and Croatian Science Foundation, Croatia ; Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Cuba ; Ministry of Education, Youth and Sports of the Czech Republic, Czech Republic ; Danish National Research Foundation (DNRF) , The Carlsberg Foundation and The Danish Council for Independent Research | Natural Sciences, Denmark ; Helsinki Institute of Physics (HIP), Finland ; Commissariat à l'Energie Atomique (CEA) and Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) and Centre National de la Recherche Scientifique (CNRS), France ; Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF) and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany ; Ministry of Education, Research and Religious Affairs, Greece ; National Research, Development and Innovation Office, Hungary ; Department of Atomic Energy Government of India (DAE), India ; Indonesian Institute of Science, Indonesia ; Centro Fermi – Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare (INFN), Italy ; Institute for Innovative Science and Technology, Nagasaki Institute of Applied Science (IIST) , Japan Society for the Promotion of Science (JSPS) KAKENHI and Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan ; Consejo Nacional de Ciencia y Tecnología (CONACYT) , through Fondo de Cooperación Internacional en Ciencia y Tecnología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA), Mexico ; Nationaal instituut voor subatomaire fysica (Nikhef), Netherlands ; The Research Council of Norway, Norway ; Commission on Science and Technology for Sustainable Development in the South (COMSATS), Pakistan ; Pontificia Universidad Católica del Perú, Peru ; Ministry of Science and Higher Education and National Science Centre, Poland ; Ministry of Education and Scientific Research , Institute of Atomic Physics and Romanian National Agency for Science, Technology and Innovation, Romania ; Joint Institute for Nuclear Research (JINR) , Ministry of Education and Science of the Russian Federation and National Research Centre Kurchatov Institute, Russia ; Ministry of Education, Science, Research and Sport of the Slovak Republic, Slovakia ; National Research Foundation of South Africa, South Africa ; Korea Institute of Science and Technology Information and National Research Foundation of Korea (NRF), South Korea ; Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) and Ministerio de Ciencia e Innovación, Spain ; Knut & Alice Wallenberg Foundation (KAW) and Swedish Research Council (VR), Sweden; European Organization for Nuclear Research, Switzerland ; National Science and Technology Development Agency (NSDTA) , Office of the Higher Education Commission under NRU project of Thailand and Suranaree University of Technology (SUT), Thailand ; Turkish Atomic Energy Agency (TAEK), Turkey ; National Academy of Sciences of Ukraine, Ukraine ; Science and Technology Facilities Council (STFC), United Kingdom ; National Science Foundation of the United States of America (NSF) and United States Department of Energy, Office of Nuclear Physics (DOE NP), United States .
Funders | Funder number |
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Austrian Academy of Sciences and Österreichische Nationalstiftung für Forschung, Technologie und Entwicklung | |
Centro Fermi – Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionale di Fisica Nucleare | |
Czech Republic | |
Danish Council for Independent Research | Natural Sciences, Denmark | |
Helsinki Institute of Physics | |
Indonesian Institute of Science, Indonesia | |
Institute of Atomic Physics and Romanian National Agency for Science, Technology and Innovation, Romania | |
MOE of China | |
Ministry of Education, Science, Research and Sport | |
Ministry of Science, Education and Sport and Croatian Science Foundation | |
NRU | |
State Committee of Science and World Federation | |
Turkish Atomic Energy Agency | |
Yerevan Physics Institute | |
National Science Foundation | 1307461 |
U.S. Department of Energy | |
Nuclear Physics | |
Türkiye Atom Enerjisi Kurumu | |
Ministry of Higher Education and Scientific Research | |
CERN | |
Office of the Higher Education Commission | |
Institute for Innovative Science and Technology, Nagasaki Institute of Applied Science | |
Science and Technology Facilities Council | 2014 STFC Nuclear Physics CG, ST/N00261X/1, ST/M001601/1, ALICE, ST/M00340X/1, ST/L005751/1, GRIDPP, ST/J000108/1, ST/L005670/1, ST/M00158X/1, ST/M001598/1 |
National Research Foundation | |
Department of Atomic Energy, Government of India | |
Japan Society for the Promotion of Science | 15H03664, 25287048, 26610071, 26220707 |
Ministry of Education, Culture, Sports, Science and Technology | |
Danmarks Grundforskningsfond | |
Fundação de Amparo à Pesquisa do Estado de São Paulo | |
National Natural Science Foundation of China | |
Ministerstvo Školství, Mládeže a Tělovýchovy | |
Ministry of Education of the People's Republic of China | |
Bundesministerium für Bildung und Forschung | |
Carlsbergfondet | |
Ministry of Science and Technology of the People's Republic of China | |
Consejo Nacional de Ciencia y Tecnología | |
Ministry of Education and Science of the Russian Federation | |
Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
Korea Institute of Science and Technology Information | |
National Research Foundation of Korea | |
Joint Institute for Nuclear Research | |
Instituto Nazionale di Fisica Nucleare | |
Knut och Alice Wallenbergs Stiftelse | |
National Science and Technology Development Agency | |
Narodowe Centrum Nauki | |
Vetenskapsrådet | |
Ministerstwo Edukacji i Nauki | |
Ministry of Science and Technology, Taiwan | |
National Academy of Sciences of Ukraine | |
Centre National de la Recherche Scientifique | |
Financiadora de Estudos e Projetos | |
Ministerio de Ciencia e Innovación | |
Norges Forskningsråd | |
Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México | |
Ministry of National Education and Religious Affairs | |
Commissariat à l'Énergie Atomique et aux Énergies Alternatives | |
Fondo de Cooperación Internacional en Ciencia y Tecnología | |
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas | |
GSI Helmholtzzentrum für Schwerionenforschung | |
Nemzeti Kutatási Fejlesztési és Innovációs Hivatal | |
Institut National de Physique Nucléaire et de Physique des Particules | |
National Research Center "Kurchatov Institute" | |
Indian Institute of Space Science and Technology |