科研之友
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摘要
Measured second and fourth azimuthal anisotropy coefficients v(2,4)(N-part, p(T)) are scaled with the initial eccentricity epsilon(2,4)(N-part) of the collision zone and studied as a function of the number of participants N-part and the transverse momenta p(T). Scaling violations are observed for p(T) less than or similar to 3 GeV/c, consistent with a p(T)(2) dependence of viscous corrections and a linear increase of the relaxation time with p(T). These empirical viscous corrections to flow and the thermal distribution function at freeze-out constrain estimates of the specific viscosity and the freeze-out temperature for two different models for the initial collision geometry. The apparent viscous corrections exhibit a sharp maximum for p(T) greater than or similar to 3 GeV/c, suggesting a breakdown of the hydrodynamic ansatz and the onset of a change from flow-driven to suppression-driven anisotropy.
- 出版日期2010-9-30
