Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at root s(NN)=2.76 TeV
ALICE Collaboration (ukupan broj autora: 987)
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We report the measurement of a new observable of jet quenching in central Pb-Pb collisions at root s(NN) = 2.76 TeV, based on the semi-inclusive rate of charged jets recoiling from a high transverse momentum (high-p T) 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 LT p(T,jet)(ch) LT 100 GeV. Reference distributions for pp collisions at root s = 2.76TeV are calculated using Monte Carlo and NLO pQCD methods, which are validated by comparing with measurements in pp collisions at root s = 7TeV. 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 wit...hin 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.
Ključne reči:Quark gluon plasma / Jet physics / Heavy Ions
Izvor:Journal of High Energy Physics, 2015, 9, 1-42
- Grid centres, Worldwide LHC Computing Grid (WLCG) collaboration, State Committee of Science, World Federation of Scientists (WFS), Swiss Fonds Kidagan, Armenia, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Financiadora de Estudos e Projetos (FINEP), Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), National Natural Science Foundation of China (NSFC), Chinese Ministry of Education (CMOE), Ministry of Science and Technology of China (MSTC), Ministry of Education and Youth of the Czech Republic, Danish Natural Science Research Council, Carlsberg Foundation, Danish National Research Foundation, European Research Council under the European Community, Helsinki Institute of Physics, Academy of Finland, French CNRS-IN2P3, Region Pays de Loire, Region Alsace, Region Auvergne and CEA, France, German Bundesministerium fur Bildung, Wissenschaft, Forschung und Technologie (BMBF), Helmholtz Association, General Secretariat for Research and Technology, Ministry of Development, Greece, Hungarian Orszagos Tudomanyos Kutatasi Alappgrammok (OTKA), National Office for Research and Technology (NKTH), Department of Atomic Energy and Department of Science and Technology of the Government of India, Istituto Nazionale di Fisica Nucleare (INFN), Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Italy, MEXT Grant-in-Aid for Specially Promoted Research, Japan, Joint Institute for Nuclear Research, Dubna, National Research Foundation of Korea (NRF), Consejo Nacional de Cienca y Tecnologia (CONACYT), Direccion General de Asuntos del Personal Academico (DGAPA), Mexico: Amerique Latine Formation academique - European Commission (ALFA-EC), EPLANET Program (European Particle Physics Latin American Network) Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands, Research Council of Norway (NFR), National Science Centre, Poland, Ministry of National Education/Institute for Atomic Physics and Consiliul National al Cercetarii Stiintifice - Executive Agency for Higher Education Research Development and Innovation Funding (CNCS-UEFISCDI) - Romania, Ministry of Education and Science of Russian Federation, Russian Academy of Sciences, Russian Federal Agency of Atomic Energy, Russian Federal Agency for Science and Innovations, Russian Foundation for Basic Research, Ministry of Education of Slovakia, Department of Science and Technology, South Africa, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), E-Infrastructure shared between Europe and Latin America (EELA), Ministerio de Economia y Competitividad (MINECO) of Spain, Xunta de Galicia (Conselleria de Educacion), Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Cubaenergia, Cuba, IAEA (International Atomic Energy Agency), Swedish Research Council (VR), Knut and Alice Wallenberg Foundation (KAW), Ukraine Ministry of Education and Science, United Kingdom Science and Technology Facilities Council (STFC), United States Department of Energy, United States National Science Foundation, State of Texas, State of Ohio, Ministry of Science, Education and Sports of Croatia and Unity through Knowledge Fund, Croatia, Council of Scientific and Industrial Research (CSIR), New Delhi, India