Born-Infeld Strings Tunneling to D-branes

Recent work on solutions to the Born-Infeld theory used to describe D-branes suggests that fundamental strings can be viewed, in a certain limit, as D-branes whose worldvolumes have collapsed to string-like configurations. Here we address the possibility of undoing this collapse, by inducing the string to tunnel to an extended brane configuration. Using semiclassical methods we argue that, by putting one of these Born-Infeld strings in the background of a uniform 4-form RR field strength, the string can nucleate a spheroidal bulge of D2-brane, or, if the string is wrapped around a small enough circle, it can tunnel to a toroidal D2-brane. This process can also be interpreted in terms of the M2-brane. We also address the extension to other D$p$-branes, and discuss the range of validity of the approximations involved.Comment: 13 pages, 2 figure

Black Hole Production at a TeV

In this talk I briefly discuss some features of a striking signature of TeV quantum gravity/strings and large extra dimensions: the production of exotic objects such as black holes, and their stringy precursors, the string resonances at large masses which can be dubbed `string balls'. The focus is on aspects less frequently discussed in other reviews of this subject.Comment: 6 pages. Invited talk at the 12th Workshop on General Relativity and Gravitation, Tokyo, November 25-28, 200

Exact Gravitational Dual of a Plasma Ball

We present an exact solution for a black hole localized near an infrared wall in four-dimensional anti-deSitter space. By computing the holographic stress tensor we show that the CFT dual of the black hole is a 2+1-dimensional ball (i.e., a disk) of plasma at finite temperature, surrounded by vacuum. This confirms some earlier conjectures about plasma balls in AdS/CFT. We also estimate the value of the surface tension for the ball. The solution displays a number of peculiarities, most notably a non-trivial curvature of the boundary geometry, as well as other properties associated to the vanishing deconfinement temperature of the set up. We discuss how these features are related to specific physics at the infrared and ultraviolet boundaries for this solution, and should not be generic properties of plasma balls.Comment: 23 pages, 3 figure

Holographic superconductivity in the large D expansion

We study holographic superconductivity by expanding the equations in the inverse of the number of spacetime dimensions D. We obtain an analytic expression for the critical temperature as a function of the conformal dimension of the condensate operator. Its accuracy for 3+1-dimensional superconductors is better than 15%. The analysis reveals a simple, and quantitative, explanation for the onset of the superconducting instability, as well as universal features of holographic superconductivity in the large D limit. In particular, this allows to easily compute the effects of backreaction on the critical temperature.Comment: 21 pages, 7 figures. v2: minor clarifications, refs added, lighter pdf fil