2008/06/02 by Steven S. Gubser, Silviu S. Pufu, Fabio D. Rocha · 1 citation
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1088/1126-6708/2008/08/085
published as JHEP 0808:085,2008 · 33 pages, 3 figures
We explain a method for computing the bulk viscosity of strongly coupled thermal plasmas dual to supergravity backgrounds supported by one scalar field. Whereas earlier investigations required the computation of the leading dissipative term in the dispersion relation for sound waves, our method requires only the leading frequency dependence of an appropriate Green's function in the low-frequency limit. With a scalar potential chosen to mimic the equation of state of QCD, we observe a slight violation of the lower bound on the ratio of the bulk and shear viscosities conjectured in arXiv:0708.3459.