Shear viscosity to entropy density ratio in nuclear multifragmentation

TL;DR

This paper calculates the shear viscosity to entropy density ratio in nuclear multifragmentation, revealing a temperature dependence similar to water and a minimum near the phase transition, indicating liquid-gas phase transition behavior.

Contribution

It introduces an extended statistical multifragmentation model to analyze eta/s in nuclear systems, highlighting its behavior near phase transition points.

Findings

eta/s exhibits a minimum near the critical temperature

The temperature dependence of eta/s resembles that of water

Freeze-out volume and symmetry energy influence eta/s

Abstract

Nuclear multifragmentation in intermediate energy heavy ion collisions has long been associated with liquid-gas phase transition. We calculate the shear viscosity to entropy density ratio eta/s for an equilibrated system of nucleons and fragments produced in multifragmentation within an extended statistical multifragmentation model. The temperature dependence of eta/s exhibits surprisingly similar behavior as that for water. In the coexistence phase of fragments and light particles, the ratio eta/s reaches a minimum of comparable depth as that for water in the vicinity of the critical temperature for liquid-gas phase transition. The effects of freeze-out volume and surface symmetry energy on eta/s in multifragmentation are studied.