SHEAR VISCOSITY OF NUCLEAR MATTER

Shear viscosity  ῃ is calculated for the nuclear matter described as a system of interactingnucleons with the van der Waals (VDW) equation of state. The Boltzmann-Vlasov kineticequation is solved in terms of the plane waves of the collective overdamped motion. In thefrequent collision regime, the shear viscosity depends on the particle number density n throughthe mean-field parameter a which describes attractive forces in the VDW equation. In thetemperature region T = 15 ÷ 40 MeV, a ratio of the shear viscosity to the entropy density sis smaller than 1 at the nucleon number density n = (0.5÷1.5) n0, where n0 = 0.16 fm^-3 isthe particle density of equilibrium nuclear matter at zero temperature. A minimum of the ῃ/sratio takes place somewhere in a vicinity of the critical point of the VDW system. Large valuesof ῃ/s >> 1 are however found in both the low density, n << n0, and high density, n > 2n0,regions. This makes the ideal hydrodynamic approach inapplicable for these densities.

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J. Dąbrowski
S.G. Rohoziński
A. Sobiczewski