404 research outputs found
On the oscillation of species
We describe a new class of BPS objects called magnetubes: their supersymmetry is determined by their magnetic charges, while their electric charges can oscillate freely between different species. We show how to incorporate these objects into microstate geometries and create BPS solutions in which the charge densities rotate through different U(1) species as one moves around a circle within the microstate geometry. Our solutions have the same “time-like” supersymmetry as five-dimensional, three-charge black holes but, in various parts of the solution, the supersymmetry takes the “null” form that is normally associated with magnetic charges. It is this property that enables the species oscillation of magnetubes to be compatible with supersymmetry. We give an example in which the species oscillate non-trivially around a circle within a microstate geometry, and yet the energy-momentum tensor and metric are completely independent of this circle: only the amplitude of the oscillation influences the metric
Flavour Democracy in Strong Unification
We show that the fermion mass spectrum may naturally be understood in terms
of flavour democratic fixed points in supersymmetric theories which have a
large domain of attraction in the presence of "strong unification". Our
approach provides an alternative to the approximate Yukawa texture zeroes of
the Froggatt-Nielsen mechanism. We discuss a particular model based on a broken
gauged family symmetry which illustrates our approach.Comment: 21 Pages plain latex; includes 5 eps figure
Nonsupersymmetric smooth geometries and D1-D5-P bound states
We construct smooth nonsupersymmetric soliton solutions with D1-brane, D5-brane, and momentum charges in type IIB supergravity compactified on T4Ă—S1, with the charges along the compact directions. This generalizes previous studies of smooth supersymmetric solutions. The solutions are obtained by considering a known family of U(1)Ă—U(1) invariant metrics, and studying the conditions imposed by requiring smoothness. We discuss the relation of our solutions to states in the CFT describing the D1-D5 system and describe various interesting features of the geometry
Hot multiboundary wormholes from bipartite entanglement
We analyze the 1+1 CFT states dual to hot (time-symmetric) 2+1 multiboundary AdS wormholes. These are black hole geometries with high local temperature, asymptotically-AdS3 regions, and arbitrary internal topology. The dual state at t = 0 is defined on n circles. We show these to be well-described by sewing together tensor networks corresponding to thermofield double states. As a result, the entanglement is spatially localized and bipartite: away from particular boundary points ('vertices') any small connected region A of the boundary CFT is entangled only with another small connected region B, where B may lie on a different circle or may be a different part of the same circle. We focus on the pair-of-pants case, from which more general cases may be constructed. We also discuss finite-temperature corrections, where we note that the states involve a code subspace in each circle
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
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
expansion.Comment: 15 pages, 2 figures, Late
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
Solitons in Five Dimensional Minimal Supergravity: Local Charge, Exotic Ergoregions, and Violations of the BPS Bound
We describe a number of striking features of a class of smooth solitons in
gauged and ungauged minimal supergravity in five dimensions. The solitons are
globally asymptotically flat or asymptotically AdS without any Kaluza-Klein
directions but contain a minimal sphere formed when a cycle pinches off in the
interior of the spacetime. The solutions carry a local magnetic charge and many
have rather unusual ergosurfaces. Perhaps most strikingly, many of the solitons
have more electric charge or, in the asymptotically AdS case, more electric
charge and angular momentum than is allowed by the usual BPS bound. We comment
on, but do not resolve, the new puzzle this raises for AdS/CFT.Comment: 60 pages, 12 figures, 3 table
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