Observation of Direct-Photon Collective Flow in Au plus Au Collisions at root s(NN)=200 GeV
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
---|---|
Data(s) |
07/11/2013
07/11/2013
2012
|
Resumo |
The second Fourier component v(2) of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (p(T)) of 1-12 GeV/c in Au + Au collisions at root s(NN) = 200 GeV. Previous measurements of this quantity for hadrons with p(T) < 6 GeV/c indicate that the medium behaves like a nearly perfect fluid, while for p(T) > 6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for p(T) > 4 GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the p(T) < 4 GeV/c region dominated by thermal photons, we find a substantial direct-photon v(2) comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v(2). Office of Nuclear Physics in the Office of Science of the Department of Energy National Science Foundation Abilene Christian University Research Council Research Foundation of SUNY Ministry of Education, Culture, Sports, Science, and Technology (Japan) Japan Society for the Promotion of Science (Japan) Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Brazil) Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Brazil) Natural Science Foundation of China (P.R. China) Ministry of Education, Youth and Sports (Czech Republic) Centre National de la Recherche Scientifique, Commissariat a lEnergie Atomique, (France) Institut National de Physique Nucleaire et de Physique des Particules (France) Bundesministerium fur Bildung und Forschung (Germany) Deutscher Akademischer Austausch Dienst (Germany) Alexander von Humboldt Stiftung (Germany) Hungarian National Science Fund, OTKA (Hungary) Department of Atomic Energy (India) Department of Science and Technology (India) Israel Science Foundation (Israel) National Research Foundation (Korea) WCU program of the Ministry Education Science and Technology (Korea) Ministry of Education and Science, Russian Academy of Sciences, Federal Agency of Atomic Energy (Russia) VR (Sweden) Wallenberg Foundation (Sweden) U.S. Civilian Research and Development Foundation for the Independent States of the Former Soviet Union U.S.Hungarian Fulbright Foundation for Educational Exchange U.S.-Israel Binational Science Foundation |
Identificador |
PHYSICAL REVIEW LETTERS, COLLEGE PK, v. 109, n. 12, supl. 1, Part 1, pp. 3028-3035, SEP 19, 2012 0031-9007 http://www.producao.usp.br/handle/BDPI/43096 10.1103/PhysRevLett.109.122302 |
Idioma(s) |
eng |
Publicador |
AMER PHYSICAL SOC COLLEGE PK |
Relação |
PHYSICAL REVIEW LETTERS |
Direitos |
openAccess Copyright AMER PHYSICAL SOC |
Palavras-Chave | #PHENIX #DETECTORS #DETECTORES #FÍSICA MULTIDISCIPLINAR #PHENIX #PHYSICS, MULTIDISCIPLINARY |
Tipo |
article original article publishedVersion |