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arXiv · 0901.4908

Does interferometry probe thermalization?

Clement Gombeaud·Tuomas Lappi·Jean-Yves Ollitrault
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Abstract

We carry out a systematic study of interferometry radii in ultrarelativistic heavy-ion collisions within a two-dimensional transport model. We compute the transverse radii R_o and R_s as a function of p_t for various values of the Knudsen number, which measures the degree of thermalization in the system. They converge to the hydrodynamical limit much more slowly (by a factor 3) than elliptic flow. This solves most of the HBT puzzle for central collisions: R_o/R_s is in the range 1.1-1.2 for realistic values of the Knudsen number, much closer to experimental data ($\simeq 1$) than the value 1.5 from hydrodynamical calculations. The p_t dependence of R_o and R_s, which is usually said to reflect collective flow, also has a very limited sensitivity to the degree of thermalization. We then study the azimuthal oscillations of R_o, R_s, and R_{os} for non central collisions. Their amplitudes depend little on the Knudsen number, and reflect the eccentricity of the overlap area between the two nuclei.

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Clement Gombeaud, Tuomas Lappi, Jean-Yves Ollitrault. 2009-05-26. Does interferometry probe thermalization?. https://doi.org/10.1103/physrevc.79.054914

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