Shear viscosity from nuclear stopping

TL;DR

This paper uses a Boltzmann transport model to connect nuclear stopping data with shear viscosity, enabling estimation of nuclear matter's viscosity and its proximity to quantum limits.

Contribution

It establishes a correlation between stopping observables and shear viscosity, and tunes the in-medium nucleon-nucleon cross section to match experimental data.

Findings

Estimated shear viscosity of nuclear matter.

Calculated shear viscosity to entropy density ratio.

System's proximity to quantum viscosity limit.

Abstract

Within a Boltzmann transport model, we demonstrate correlation between stopping observables and shear viscosity in central nuclear collisions at intermediate energies (on the order of 10 to 1000 MeV/nucleon). The correlation allows us to assess the viscosity of nuclear matter, by tuning the in-medium nucleon-nucleon cross section in our transport model to agree with nuclear stopping data. We also calculate the ratio of shear viscosity to entropy density to determine how close the system is to the universal quantum lower limit proposed in the context of ultrarelativistic heavy ion collisions.