Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature

0370231 - FZÚ 2012 RIV US eng J - Článek v odborném periodiku
Adare, A. - Afanasiev, S. - Aidala, C. - Kubart, J. - Mašek, L. - Mikeš, P. - Tomášek, Lukáš - Vrba, Václav
Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature.
Physical Review Letters. Roč. 104, č. 13 (2010), "132301-1"-"132301-6". ISSN 0031-9007. E-ISSN 1079-7114
Grant CEP: GA MŠMT LC527; GA MŠMT LA08015
Výzkumný záměr: CEZ:AV0Z10100502
Klíčová slova: p p: colliding beams * nucleus nucleus: colliding beams * scattering: heavy ion * photon: direct production * photon: yield * PHENIX
Kód oboru RIV: BF - Elementární částice a fyzika vys. energií
Impakt faktor: 7.621, rok: 2010
http://arxiv.org/pdf/arXiv:0804.4168

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 yield above hadronic sources is observed. Treating the excess as internal conversions, the invariant yield of direct photons is deduced. In central Au+Au collisions, the excess of direct photon yield over p+p is exponential in transverse momentum, with inverse slope T = 221 +/- 19 (stat) +/- 19 (syst) MeV. Hydrodynamical models with initial temperatures ranging from 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 to quark gluon plasma at ~ 170 MeV.
Trvalý link: http://hdl.handle.net/11104/0204091