Measurement of Direct Photons in Au plus Au Collisions at root s(NN)=200 GeV
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
05/11/2013
05/11/2013
2012
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Resumo |
We report the measurement of direct photons at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/c < pT < 22 GeV/c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R-AA was calculated as a function of p(T) for different Au + Au collision centralities using the measured p + p direct photon spectrum and compared to theoretical predictions. R-AA was found to be consistent with unity for all centralities over the entire measured pT range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R-AA from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement. 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 Dean of the College of Arts and Sciences, Vanderbilt University (USA) Ministry of Education, Culture, Sports, Science, and Technology 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) Centre National de la Recherche Scientifique, Commissariat a l'Energie Atomique, (France) Institut National de Physique Nucleaire et de Physique des Particules (France) Ministry of Industry, Science and Tekhnologies, (Germany) 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) Israel Science Foundation (Israel) National Research Foundation (Korea) WCU program of the Ministry Education Science and Technology (Korea) Ministry of Education and Science, (Russia) Russian Academy of Sciences, (Russia) Federal Agency of Atomic Energy (Russia) VR Wallenberg Foundation (Sweden) U.S. Civilian Research and Development Foundation for the Independent States of the Former Soviet Union US-Hungarian NSF-OTKA-MTA US-Israel Binational Science Foundation |
Identificador |
PHYSICAL REVIEW LETTERS, COLLEGE PK, v. 109, n. 15, supl. 1, Part 1, pp. 1541-1549, OCT 9, 2012 0031-9007 http://www.producao.usp.br/handle/BDPI/41921 10.1103/PhysRevLett.109.152302 |
Idioma(s) |
eng |
Publicador |
AMER PHYSICAL SOC COLLEGE PK |
Relação |
PHYSICAL REVIEW LETTERS |
Direitos |
openAccess Copyright AMER PHYSICAL SOC |
Palavras-Chave | #PHYSICS, MULTIDISCIPLINARY |
Tipo |
article original article publishedVersion |