210 articles – 1947 Notices  [english version]
 HAL : in2p3-00277382, version 1
 arXiv : 0804.4168
 Physical Review Letters 104 (2010) 132301
 Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature
 PHENIX Collaboration(s)
 (2010)
 The production of low mass e+e- pairs for m_{e+e-} < 300 MeV/c^2 and 1 < p_T <5 GeV/c is measured in p+p and Au+Au collisions at sqrt(s_NN)=200 GeV. Enhanced e+e- pair yield above hadronic sources is observed in Au+Au collisions. Treating the excess as internal conversion of direct photons, the invariant yield of direct photons is deduced. In central Au+Au collisions, the excess over p+p is exponential in p_T}, with inverse slope T = 221 +/- 23 (stat) +/- 18 (syst) MeV. Hydrodynamical models with initial temperatures T_init ~ 300-600 MeV at times of 0.6 - 0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition at ~ 170 MeV.
 Thème(s) : Physique/Physique Nucléaire Expérimentale
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0804.4168
 in2p3-00277382, version 1 http://hal.in2p3.fr/in2p3-00277382 oai:hal.in2p3.fr:in2p3-00277382 Contributeur : Dominique Girod <> Soumis le : Mardi 6 Mai 2008, 11:52:25 Dernière modification le : Mardi 10 Avril 2012, 11:10:11