Effects of partial thermalization on HBT interferometry Original Research Article

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 transverse radii Ro and Rs as functions of pt for various values of the Knudsen number, which measures the degree of thermalization in the system. For realistic values of the Knudsen number estimated from v2 data, we obtain Ro/Rs≃1.2, much closer to data than standard hydrodynamical results. Femtoscopic observables vary little with the degree of thermalization. Azimuthal oscillations of the radii in non central collisions do not provide a good probe of thermalization.