Bubbles Unbound: Bubbles of Nothing Without Kaluza-Klein

I present analytic time symmetric initial data for five dimensions describing ``bubbles of nothing'' which are asymptotically flat in the higher dimensional sense, i.e. there is no Kaluza-Klein circle asymptotically. The mass and size of these bubbles may be chosen arbitrarily and in particular the solutions contain bubbles of any size which are arbitrarily light. This suggests the solutions may be important phenomenologically and in particular I show that at low energy there are bubbles which expand outwards, suggesting a new possible instability in higher dimensions. Further, one may find bubbles of any size where the only region of high curvature is confined to an arbitrarily small volume.Comment: 27 pages, 2 figures, v2: minor changes, published versio

On Witten's Instability and Winding Tachyons

We investigate, from a spacetime perspective, some aspects of Horowitz's recent conjecture that black strings may catalyze the decay of Kaluza-Klein spacetimes into a bubble of nothing. We identify classical configurations that interpolate between flat space and the bubble, and discuss the energetics of the transition. We investigate the effects of winding tachyons on the size and shape of the barrier and find no evidence at large compactification radius that tachyons enhance the tunneling rate. For the interesting radii, of order the string scale, the question is difficult to answer due to the failure of the $\alpha^\prime$ expansion.Comment: 15 pages, 2 figures, Late

Strings in extremal BTZ black holes

We study the spectrum of the worldsheet theory of the bosonic closed string in the massless and extremal rotating BTZ black holes. We use a hyperbolic Wakimoto representation of the SL(2,R) currents to construct vertex operators for the string modes on these backgrounds. We argue that there are tachyons in the twisted sector, but these are not localised near the horizon. We study the relation to the null orbifold in the limit of vanishing cosmological constant. We also discuss the problem of extending this analysis to the supersymmetric case.Comment: 20 pages, no figure

Tachyon Condensation and Black Strings

We show that under certain conditions, closed string tachyon condensation produces a topology changing transition from black strings to Kaluza-Klein "bubbles of nothing." This can occur when the curvature at the horizon is much smaller than the string scale, so the black string is far from the correspondence point when it would make a transition to an excited fundamental string. This provides a dramatic new endpoint to Hawking evaporation. A similar transition occurs for black p-branes, and can be viewed as a nonextremal version of a geometric transition. Applications to AdS black holes and the AdS soliton are also discussed.Comment: 23 pages, 1 figure, v2: references adde

On fluctuations of closed string tachyon solitons

We discuss fluctuations on solitons in the dilaton/graviton/tachyon system using the low energy effective field theory approach. It is shown that closed string solitons are free of tachyons in this approximation, regardless of the exact shape of the tachyon potential.Comment: 13 pages, 1 figure, uses JHEP3.cl

Closed string tachyons, flips and conifolds

Following the analysis of tachyons and orbifold flips described in hep-th/0412337, we study nonsupersymmetric analogs of the supersymmetric conifold singularity and show using their toric geometry description that they are nonsupersymmetric orbifolds of the latter. Using linear sigma models, we see that these are unstable to localized closed string tachyon condensation and exhibit flip transitions between their two small resolutions (involving 2-cycles), in the process mediating mild dynamical topology change. Our analysis shows that the structure of these nonsupersymmetric conifolds as quotients of the supersymmetric conifold obstructs the 3-cycle deformation of such singularities, suggesting that these nonsupersymmetric conifolds decay by evolving towards their stable small resolutions.Comment: Latex, 22 pgs, 2 figs. v4: matches JHEP version, 29 pgs, 3 figures, more elaborate Introduction, various clarifications adde

Compaction of Rods: Relaxation and Ordering in Vibrated, Anisotropic Granular Material

We report on experiments to measure the temporal and spatial evolution of packing arrangements of anisotropic, cylindrical granular material, using high-resolution capacitive monitoring. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical vibrations evolve to a dense, highly ordered, nematic state in which the long particle axes align with the vertical tube walls. We find that the orientational ordering process is reflected in a characteristic, steep rise in the local packing fraction. At any given height inside the packing, the ordering is initiated at the container walls and proceeds inward. We explore the evolution of the local as well as the height-averaged packing fraction as a function of vibration parameters and compare our results to relaxation experiments conducted on spherically shaped granular materials.Comment: 9 pages incl. 7 figure

A Lifshitz Black Hole in Four Dimensional R^2 Gravity

We consider a higher derivative gravity theory in four dimensions with a negative cosmological constant and show that vacuum solutions of both Lifshitz type and Schr\"{o}dinger type with arbitrary dynamical exponent z exist in this system. Then we find an analytic black hole solution which asymptotes to the vacuum Lifshitz solution with z=3/2 at a specific value of the coupling constant. We analyze the thermodynamic behavior of this black hole and find that the black hole has zero entropy while non-zero temperature, which is very similar to the case of BTZ black holes in new massive gravity at a specific coupling. In addition, we find that the three dimensional Lifshitz black hole recently found by E. Ayon-Beato et al. has a negative entropy and mass when the Newton constant is taken to be positive.Comment: 11 pages, no figure; v2, a minor error correcte

Non-relativistic metrics with extremal limits

We present solutions of type IIB supergravity with z=2 Schrodinger asymptotics that admit an extremal limit, i.e. the black hole horizon has a double zero. These solutions are obtained as TsT transformations of the charged planar black hole in AdS_5 \times S^5. Unlike the uncharged solution, the Ramond-Ramond two-form is turned on. We study the thermodynamic properties of these new solutions, and we show that the ratio of shear viscosity to entropy density is 1/4\pi even in the extremal limit. We also consider the TsT-transformed soliton and show that, for a special radius of the compact circle, there is a confinement-deconfinement phase transition at zero temperature between the soliton and black hole phases.Comment: 23 pages, references and clarifications added, typos corrected, restriction in phase transition due to equation 6.5 emphasized; published versio