54 research outputs found
Kinematic space for conical defects
Kinematic space can be used as an intermediate step in the AdS/CFT dictionary
and lends itself naturally to the description of diffeomorphism invariant
quantities. From the bulk it has been defined as the space of boundary anchored
geodesics, and from the boundary as the space of pairs of CFT points. When the
bulk is not globally AdS the appearance of non-minimal geodesics leads to
ambiguities in these definitions. In this work conical defect spacetimes are
considered as an example where non-minimal geodesics are common. From the bulk
it is found that the conical defect kinematic space can be obtained from the
AdS kinematic space by the same quotient under which one obtains the defect
from AdS. The resulting kinematic space is one of many equivalent
fundamental regions. From the boundary the conical defect kinematic space can
be determined by breaking up OPE blocks into contributions from individual bulk
geodesics. A duality is established between partial OPE blocks and bulk fields
integrated over individual geodesics, minimal or non-minimal.Comment: 29 pages, 9 figures. As published in JHE
Folding Branes
We study classical dynamics of a probe Dp-brane moving in a background
sourced by a stack of Dp-branes. In this context the physics is similar to that
of the effective action for open-string tachyon condensation, but with a
power-law runaway potential. We show that small inhomogeneous ripples of the
probe brane embedding grow with time, leading to folding of the brane as it
moves. We give a full nonlinear analytical treatment of inhomogeneous brane
dynamics, suitable for the Dirac-Born-Infeld + Wess-Zumino theory with
arbitrary runaway potential, in the case where the source branes are BPS. In
the near-horizon geometry, the inhomogeneous brane motion has a dual
description in terms of free streaming of massive relativistic test particles
originating from the initial hypersurface of the probe brane. We discuss
limitations of the effective action description around loci of self-crossing of
the probe brane (caustics). We also discuss the effect of brane folding in
application to the theory of cosmological fluctuations in string theory
inflation.Comment: 15 pages, 2 figures, LaTe
TASI lectures on black holes in string theory
This is a write-up of introductory lectures on black holes in string theory
given at TASI-99. Topics discussed include: Black holes, thermodynamics and the
Bekenstein-Hawking entropy, the information problem; supergravity actions,
conserved quantum numbers, supersymmetry and BPS states, units and duality,
dimensional reduction, solution-generating; extremal M-branes and D-branes,
smearing, probe actions, nonextremal branes, the Gregory-Laflamme instability;
breakdown of supergravity and the Correspondence Principle, limits in parameter
space, singularity resolution; making black holes with branes,
intersection-ology, explicit d=5,4 examples; string/brane computations of
extremal black hole entropy in d=5,4, rotation, fractionation; non-extremality
and entropy, the link to BTZ black holes, Hawking radiation and absorption
cross-sections in the string/brane and supergravity pictures.Comment: 80 pages LaTeX, 8 figures (v2: references added[apologies to wronged
Authors] and a few other minor modifications
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