Shear viscosity to electric conductivity ratio of the QGP

The transport coefficients of strongly interacting matter are currently subject of intense theoretical and phenomenological studies due to their relevance for the characterization of the quark-gluon plasma produced in ultra-relativistic heavy-ion collisions (uRHIC). We predict that (η/s)/(σel/T ), independently on the running coupling αs(T), should increase up to about ∼ 20 for T → Tc, while it goes down to a nearly flat behavior around ∼ 4 for T ≥ 4 Tc. Therefore we find a stronger T-dependence of σel/T with respect to η/s that in a quasiparticle approach is constrained by lQCD thermodynamics. A conformal theory, instead, predicts a similar T dependence of η/s and σel/T