miércoles, 28 de mayo de 2008

Holography and unquenched quark-gluon plasmas




Holography and unquenched quark-gluon plasmas



G. A. Canals (Max Planck Inst. -U., Stuttgart) , F. Bigazzi (Brussels U., PTM & Intl. Solvay Inst., Brussels) , A.L. Cotrone (Barcelona U., ECM & Barcelona, IFAE) , Jose D. Edelstein (Santiago de Compostela U. & Santiago de Compostela U., IGFAE & CECS, Valdivia)
UB-ECM-PF-08-03, CECS-PHY-08-03, March 2008. 30pp.
e-Print: hep-th/0802825

We employ the string/gauge theory correspondence to study properties of strongly coupled quark-gluon plasmas in thermal gauge theories with a large number of colors and flavors. In particular, we analyze non-critical string duals of conformal (S)QCD, as well as ten dimensional wrapped fivebrane duals of SQCD-like theories. We study general properties of the dual plasmas, including the drag force exerted on a probe quark and the jet quenching parameter. We find that these plasma observables depend on the number of colors and flavors in the ``QCD dual''; in particular, we find that the jet quenching parameter increases linearly with N_f/N_c at leading order in the probe limit. In the ten dimensional case we find a non trivial drag coefficient but a vanishing jet quenching parameter. We comment on the relation of this result with total screening and argue that the same features are shared by all known plasmas dual to fivebranes in ten dimensions. We also construct new D5 black hole solutions with spherical horizon and show that they exhibit the same features.

We consider the problem of a self-interacting scalar field nonminimally coupled to the three-dimensional BTZ metric such that its energy-momentum tensor evaluated on the BTZ metric vanishes. We prove that this system is equivalent to a self-dual system composed by a set of two first-order equations. The self-dual point is achieved by fixing one of the coupling constant of the potential in terms of the nonminimal coupling parameter. At the self-dual point and up to some boundary terms, the matter action evaluated on the BTZ metric is bounded below and above. These two bounds are saturated simultaneously yielding to a vanishing action for configurations satisfying the set of self-dual first-order equations.

Canals Gustavo Adolfo
Dr. Física Teórica, Ph.D.math.
Max Planck Inst. - Universität Stuttgart

adolfocanals@educ.ar


No hay comentarios: