title: Small shear viscosity of a quark-gluon plasma implies strong jet quenching.
abstract: We derive an expression relating the transport parameter q and the shear viscosity eta of a weakly coupled quark-gluon plasma. A deviation from this relation can be regarded as a quantitative measure of "strong coupling" of the medium. The ratio T{3}/q, where T is the temperature, is a more broadly valid measure of the coupling strength of the medium than eta/s, where s denotes the entropy density. Different estimates of q derived from existing Relativistic Heavy Ion Collider data are shown to imply radically different structures of the produced matter.
authors.affiliation: Department of Physics, Duke University, Durham, NC 27708, USA.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Majumder
authors.forename: Berndt
authors.initials: B
authors.lastname: Müller
authors.forename: Xin-Nian
authors.initials: XN
authors.lastname: Wang