Is anisotropic flow really acoustic?

2013/01/02 by Lacey, Roy A., Gu, Yi, Gong, X. +5 · 1 citation
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th)

paper · doi:10.48550/arxiv.1301.0165

Abstract

The flow harmonics for charged hadrons (v_n) and their ratios (v_n/v₂)_{n≥ 3}, are studied for a broad range of transverse momenta (p_T) and centrality (cent) in Pb+Pb collisions at √s_NN= 2.76 TeV. They indicate characteristic scaling patterns for viscous damping consistent with the dispersion relation for sound propagation in the plasma produced in the collisions. These scaling properties are not only a unique signature for anisotropic expansion modulated by the specific shear viscosity (η/s), they provide essential constraints for the relaxation time, a distinction between two of the leading models for initial eccentricity, as well as an extracted < η/s > value which is insensitive to the initial geometry model. These constraints could be important for a more precise determination of η/s.

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