Measuring the isotropization time of quark-gluon plasma from direct photons at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)
- Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)
We calculate transverse momentum distribution of direct photons from various sources by taking into account the initial state momentum anisotropy of quark-gluon plasma (QGP) and late stage transverse flow effects. To evaluate the photon yield from hadronic matter we include the contributions from baryon-meson reactions. The total photon yield, calculated for various combinations of initial conditions and transition temperatures, is then compared with the recent measurement of photon transverse momentum distribution by the PHENIX Collaboration. It is shown that because of the initial state anisotropy the photon yield from the QGP is larger by a factor of 8-10 than that of the isotropic case in the intermediate p{sub T} regime. It is also demonstrated that the presence of such an anisotropy can describe the PHENIX photon data better than the isotropic case in the present model. We show that the isotropization time thus extracted lies within the range 1.5{>=}{tau}{sub iso}{>=}0.5 fm/c for the initial conditions used here.
- OSTI ID:
- 21286971
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 79, Issue 5; Other Information: DOI: 10.1103/PhysRevC.79.054910; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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