Thermalization at RHIC

Ideal hydroynamics provides an excellent description of all aspects of the single-particle spectra of all hadrons with transverse momenta below about 1.5-2 GeV/c at RHIC. This is shown to require rapid local thermalization at a time scale below 1 fm/c and at energy densities which exceed the critical value for color deconfinement by an order of magnitude. The only known thermalized state at such energy densities is the quark-gluon plasma (QGP). The rapid thermalization indicates that the QGP is a strongly interacting liquid rather than the weakly interacting gas of quarks and gluons that was previously expected.Comment: Erroneous formulation on p.2 corrected. 16 pages, incl. 4 postscript figures. Invited talk presented at HADRON-RANP 2004 (IX Hadron Physics and VII Relativistics Aspects of Nuclear Physics: A Joint Meeting on QCD and QGP), Angra dos Reis, Rio de Janeiro, Brazil, March 28 - April 3, 2004. To appear in AIP Conference Proceedings (M. Bracco, M. Chiapparini, et al., eds.

Nonperturbative calculation of the shear viscosity in hot phi**4 theory in real time

Starting from the Kubo formula we calculate the shear viscosity in hot phi**4 theory nonperturbatively by resumming ladders with a real-time version of the Bethe-Salpeter equation at finite temperature. In the weak coupling limit, the generalized Fluctuation-Dissipation Theorem is shown to decouple the Bethe-Salpeter equations for the different real-time components of the 4-point function. The resulting scalar integral equation is identical with the one obtained by Jeon using diagrammatic ``cutting rules'' in the Imaginary Time Formalism.Comment: 4 pages LateX. The 2 postscript figures are now incorporated into the text, facilitating download. No other changes. Accepted by Physics Letters