On bulk viscosity and moduli decay

TL;DR

This lecture explores the relationship between bulk viscosity in Yang-Mills theory and scalar field decay rates, illustrating key thermal field theory concepts relevant to heavy ion collisions and cosmology.

Contribution

It highlights a specific link between bulk viscosity and decay rates, providing pedagogical insights into thermal QCD and scalar field dynamics.

Findings

Relationship between bulk viscosity and decay rate elucidated

Thermal field theory concepts demonstrated

Relevance to heavy ion collision hydrodynamics discussed

Abstract

This pedagogically intended lecture, one of four under the header "Basics of thermal QCD", reviews an interesting relationship, originally pointed out by Bodeker, that exists between the bulk viscosity of Yang-Mills theory (of possible relevance to the hydrodynamics of heavy ion collision experiments) and the decay rate of scalar fields coupled very weakly to a heat bath (appearing in some particle physics inspired cosmological scenarios). This topic serves, furthermore, as a platform on which a number of generic thermal field theory concepts are illustrated. The other three lectures (on the QCD equation of state and the rates of elastic as well as inelastic processes experienced by heavy quarks) are recapitulated in brief encyclopedic form.