Enhanced Production of Direct Photons in Au plus Au Collisions at root s(NN)=200 GeV and Implications for the Initial Temperature
| Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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| Data(s) |
18/04/2012
18/04/2012
2010
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| Resumo |
The production of e(+)e(-) pairs for m(e+e-) < 0.3 GeV/c(2) and 1< p(T) < 5 GeV/c is measured in p + p and Au + Au collisions at root s(NN) = 200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au + Au collisions, the excess of the direct photon yield over p + p is exponential in transverse momentum, with an inverse slope T = 221 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T(init) similar to 300-600 MeV at times of similar to 0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at similar to 170 MeV. Department of Energy (DOE) (USA) National Science Foundation NSF (USA) MEXT (Japan) JSPS - Japan Society for the Promotion of Science (Japan) CNPq (Brazil) FAPESP (Brazil) NSFC (China) MSMT (Czech Republic) Centre National de la Recherche Scientifique - IN2P3/CNRS (France) CEA (France) BMBF - Bundesministerium fur Bildung und Forschung, Germany (DAAD) Deutscher Akademischer Austausch Dienst, Germany Alexander von Humboldt Foundation (Germany) OTKA (Hungary) (DAE) Department of Atomic Energy, India ISF - Israel Science Foundation (Israel) NRF (Korea) MES Ministry of Education and Science of the Russian Federation RAS Russia Academy of Sciences FAAE (Russia) VR (Sweden) KAW (Sweden) U.S. CRDF US-Hungarian NSF-OTKA-MTA (BSF) US-Israel Binational Science Foundation |
| Identificador |
PHYSICAL REVIEW LETTERS, v.104, n.13, 2010 0031-9007 http://producao.usp.br/handle/BDPI/16078 10.1103/PhysRevLett.104.132301 |
| Idioma(s) |
eng |
| Publicador |
AMER PHYSICAL SOC |
| Relação |
Physical Review Letters |
| Direitos |
restrictedAccess Copyright AMER PHYSICAL SOC |
| Palavras-Chave | #NUCLEUS-NUCLEUS COLLISIONS #THERMAL PHOTONS #Physics, Multidisciplinary |
| Tipo |
article original article publishedVersion |