Shear viscosity of superfluid 3He-A_1 at low temperatures

TL;DR

This paper calculates the shear viscosity tensor of superfluid 3He-A_1 at low temperatures using Boltzmann equations, revealing temperature dependence and agreement with experimental data.

Contribution

It introduces a detailed Boltzmann equation approach considering interactions between normal and superfluid quasiparticles for shear viscosity calculation.

Findings

Shear viscosity components are proportional to (T/T_c)^{-2}.

Theoretical results agree with experimental measurements.

Different contributions from normal and superfluid components are characterized.

Abstract

The shear viscosity tensor of the A_1-phase of superfluid 3He is calculated at low temperatures and melting pressure, by using Boltzmann equation approach. The two normal and superfluid components take part in elements of the shear viscosity tensor differently. The interaction between normal and Bogoliubov quasiparticles in the collision integrals is considered in the binary, decay and coalescence processes. We show that the elements of the shear viscosities $\eta_{xy}$, $\eta_{xz}$ and $\eta_{zz}$ are proportional to $(T/T_c)^{-2}$. The constant of proportionality is in nearly good agreement with the experimental results of Roobol et al.