Year: 2009
Type: article
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 $\ensuremath{\simeq}3$) 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 ($\ensuremath{\simeq}1$) 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 ${R}_{\mathit{os}}$ for noncentral collisions. Their amplitudes depend little on the Knudsen number, and reflect the eccentricity of the overlap area between the two nuclei.
Source: Physical Review C
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1994959561