14-17 October 2009
Europe/Zurich timezone
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Does interferometry probe thermalization?

16 Oct 2009, 17:20
TH Auditorium (CERN)

TH Auditorium


Talk Investigating Dynamics and the EOS with Correlations Collectivity in p+p


Prof. Jean-Yves Ollitrault (Institut de Physique Theorique - CEA Saclay)


Hydrodynamical models have generally failed to describe interferometry radii measured at RHIC. In order to investigate this "HBT puzzle", we carry out a systematic study of HBT radii in ultrarelativistic heavy-ion collisions within a two-dimensional transport model. We compute the out and side radii as a function of the transverse momentum for various values of the Knudsen number, which measures the degree of thermalization in the system. In the case of central collisions, we show that the large difference between the side and out radii, which is seen in hydrodynamical models but not in data (HBT puzzle), appears only for unrealistically small values of the Knudsen number. For realistic values of the Knudsen number, our result for the ratio Ro/Rs is much closer to data than standard hydrodynamical results. The transverse momentum dependence of the radii, which is usually said to reflect collective flow, also has a very limited sensitivity to the degree of thermalization. Finally, we study the azimuthal oscillations of Ro, Rs, and R_{os} for non central collisions. Their amplitudes depend very little on the Knudsen number. In particular, the azimuthal dependence of Rs is found to reflect the initial eccentricity of the overlap area.

Primary author

Prof. Jean-Yves Ollitrault (Institut de Physique Theorique - CEA Saclay)

Presentation Materials