QCD Shear Viscosity at (almost) NLO

Understand

We compute the shear viscosity of QCD with matter, including almost all next-to-leading order corrections -- that is, corrections suppressed by one power of $g$ relative to leading order.

• We argue that the still missing terms are small.
• The next-to-leading order corrections are large and bring $\eta/s$ down by more than a factor of 3 at physically relevant couplings.
• The perturbative expansion is problematic even at $T \simeq 100$ GeV.