8 research outputs found
Hydrodynamics at RHIC -- how well does it work, where and how does it break down?
I review the successes and limitations of the ideal fluid dynamic model in
describing hadron emission spectra from Au+Au collisions at the Relativistic
Heavy Ion Collider (RHIC).Comment: 8 pages, 4 figures. Invited talk presented at Strange Quark Matter
2004 (Cape Town, Sep. 15-20, 2004). Proceedings to appear in Journal of
Physics
Transport Properties of Holographic Defects
We study the charge transport properties of fields confined to a
(2+1)-dimensional defect coupled to (3+1)-dimensional super-Yang-Mills at
large-\nc and strong coupling, using AdS/CFT techniques applied to linear
response theory. The dual system is described by \nf probe D5- or D7-branes
in the gravitational background of \nc black D3-branes. Surprisingly, the
transport properties of both defect CFT's are essentially identical -- even
though the D7-brane construction breaks all supersymmetries. We find that the
system possesses a conduction threshold given by the wave-number of the
perturbation and that the charge transport arises from a quasiparticle spectrum
which is consistent with an intuitive picture where the defect acquires a
finite width. We also examine finite- modifications arising from
higher derivative interactions in the probe brane action.Comment: 54 pages, 22 figures, references added, minor changes to figures and
comments, final version published in JHE
Viscosity in strongly interacting quantum field theories from black hole physics
The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of [h-bar]/4pikB for a large class of strongly interacting quantum field theories whose dual description involves black holes in antiâde Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids