Showing papers by "Eleftherios Papantonopoulos published in 2011"

From gravity to thermal gauge theories : the AdS/CFT correspondence

Abstract: Introduction to the AdS/CFT Correspondence- Perturbations of anti-de Sitter Black Holes- Introduction to the AdS/CFT Correspondence- Improved Holographic QCD- The Dynamics of Quark Gluon Plasma and AdS/CFT- Fluid Dynamics from Gravity- The Gauge-gravity Duality and Heavy Ion-Collisions- AdS/CFT on the Brane- Condensed Matter and AdS/CFT- Introduction to Holographic Superconductors- Flavor Superconductivity and Superfluidity- Holographic Torsion and the Prelude to Kalb-Ramond Superconductivity- Index

Scalar Hair from a Derivative Coupling of a Scalar Field to the Einstein Tensor

Abstract: We consider a gravitating system of vanishing cosmological constant consisting of an electromagnetic field and a scalar field coupled to the Einstein tensor. A Reissner-Nordstrom black hole undergoes a second-order phase transition to a hairy black hole of generally anisotropic hair at a certain critical temperature which we compute. The no-hair theorem is evaded due to the coupling between the scalar field and the Einstein tensor. Within a first order perturbative approach we calculate explicitly the properties of a hairy black hole configuration near the critical temperature and show that it is energetically favorable over the corresponding Reissner-Nordstrom black hole.

A new class of exact hairy black hole solutions

Abstract: We present a new class of black hole solutions with a minimally coupled scalar field in the presence of a negative cosmological constant. We consider an one-parameter family of self-interaction potentials parametrized by a dimensionless parameter g. When g = 0, we recover the conformally invariant solution of the Martinez–Troncoso–Zanelli (MTZ) black hole. A non-vanishing g signals the departure from conformal invariance. Thermodynamically, there is a critical temperature at vanishing black hole mass, where a higher-order phase transition occurs, as in the case of the MTZ black hole. Additionally, we obtain a branch of hairy solutions which undergo a first-order phase transition at a second critical temperature which depends on g and it is higher than the MTZ critical temperature. As g → 0, this second critical temperature diverges.

Perturbations of Gauss-Bonnet black strings in codimension-2 braneworlds

Abstract: We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term. Using the modified Lichnerowicz equation we study the metric perturbations of Gauss-Bonnet black strings in Codimension-2 Braneworlds.

Anisotropic extra dimensions

Abstract: We consider the scenario where, in a five-dimensional theory, the extra spatial dimension has different scaling than the other four dimensions. We find background maximally symmetric solutions, when the bulk is filled with a cosmological constant and at the same time it has a three-brane embedded in it. These background solutions are reminiscent of Randall-Sundrum warped metrics, with bulk curvature depending on the parameters of the breaking of diffeomorphism invariance. Subsequently, we consider the scalar perturbation sector of the theory and show that it has certain pathologies and the striking feature that in the limit where the diffeomorphism invariance is restored, there remain ghost scalar mode(s) in the spectrum.