Impact of quark quasiparticles on transport coefficients in hot QCD

Understand

We study the bulk and shear viscosity and the electrical conductivity in a quasiparticle approach to Yang-Mills theory and QCD with light and strange quarks to assess the dynamical role of quarks in transport properties at finite temperature.

• The interactions with a hot medium are embodied in effective masses of the constituents through a temperature-dependent running coupling extracted from the lattice QCD thermodynamics.
• In Yang-Mills theory, the bulk viscosity to entropy density ratio exhibits a non-monotonous structure around the phase transition temperature.
• In QCD, this is totally dissolved because of a substantial contribution from quark quasiparticles.