English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The viscosity of hadronic matter is studied using a classical evaluation ofthe scattering angle and a quantum mechanical discussion based on phase shiftsfrom a potential. Semi classical limits of the quantum theory are presented. Ahard sphere and an attractive square well potential step are each considered aswell as the combined effects of both. The lowest classical value of theviscosity for an attractive potential is shown to be a hard sphere limit. Thehigh wave number-short wavelength limits of the quantum result have scalinglaws associated with it for both the viscosity and entropy. These scaling lawsare similar to the Fraunhoher diffraction increase for the hard spheregeometric cross section. Specific examples for nuclear collisions are given.The importance of the nuclear tensor force and hard core is mentioned. Theviscosity (eta), entropy density (s) and eta/s ratio are calculated for a gasof dilute neutrons in the unitary limit of large scattering length. Away fromthe unitary limit, the ratio of the interaction radius or the scattering lengthto the interparticle spacing introduces a variable y besides the fugacity z.The isothermal compressibility is shown to impose important constraints. Theresults for eta/s are compared to the AdS/CFT string theory minimum of(1/4Pi)hbar/kb to see how close a nucleonic gas is to being a perfect fluid.The eta/s ~1hbar/kb for a neutron gas in its unitary limit. The eta/s 3hbar/kbtreating the nuclear scattering as billiard ball collisions. The minimum eta/sfor a neutron gas occurs in regions of negative isothermal compressibility andhigh fugacity where higher virial terms are important. In a neutron-protonsystem higher virial terms are associated with a liquid-gas phase transitionand critical opalescent phenomena.The type of flow-laminar,vortex, turbulent-is investigated.

Viscosity, entropy and the viscosity to entropy density ratio; how perfect is a nucleonic fluid?