19,437 research outputs found
Superdescendants of the D1D5 CFT and their dual 3-charge geometries
We describe how to obtain the gravity duals of semiclassical states in the
D1-D5 CFT that are superdescendants of a class of RR ground states. On the
gravity side, the configurations we construct are regular and asymptotically
reproduce the 3-charge D1-D5-P black hole compactified on . The
geometries depend trivially on the directions but non-trivially on the
remaining 6D space. In the decoupling limit, they reduce to asymptotically
AdS spaces that are dual to CFT states obtained by
acting with (exponentials of) the operators of the superconformal algebra. As
explicit examples, we generalise the solution first constructed in
arXiv:1306.1745 and discuss another class of states that have a more
complicated dual geometry. By using the free orbifold description of the CFT we
calculate the average values for momentum and the angular momenta of these
configurations. Finally we compare the CFT results with those obtained in the
bulk from the asymptotically region.Comment: 50 pages; v2: corrected typos; v3: corrected typos, eq. (2.9b)
simplifie
Multi-loop open string amplitudes and their field theory limit
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0This work
was supported by STFC (Grant ST/J000469/1, ‘String theory, gauge theory & duality’)
and by MIUR (Italy) under contracts 2006020509 004 and 2010YJ2NYW 00
Do the electromagnetic fields generated by mobile-phone base-stations have short-term effects on health? A response to commentaries
Soluble models in 2d dilaton gravity
A one-parameter class of simple models of two-dimensional dilaton gravity,
which can be exactly solved including back-reaction effects, is investigated at
both classical and quantum levels. This family contains the RST model as a
special case, and it continuously interpolates between models having a flat
(Rindler) geometry and a constant curvature metric with a non-trivial dilaton
field. The processes of formation of black hole singularities from collapsing
matter and Hawking evaporation are considered in detail. Various physical
aspects of these geometries are discussed, including the cosmological
interpretation.Comment: 15 pages, harvmac, 3 figure
Model of black hole evolution
From the postulate that a black hole can be replaced by a boundary on the
apparent horizon with suitable boundary conditions, an unconventional scenario
for the evolution emerges. Only an insignificant fraction of energy of order
is radiated out. The outgoing wave carries a very small part of the
quantum mechanical information of the collapsed body, the bulk of the
information remaining in the final stable black hole geometry.Comment: 9 pages, harvmac, 3 figures, minor addition
(Anti-)Evaporation of Schwarzschild-de Sitter Black Holes
We study the quantum evolution of black holes immersed in a de Sitter
background space. For black holes whose size is comparable to that of the
cosmological horizon, this process differs significantly from the evaporation
of asymptotically flat black holes. Our model includes the one-loop effective
action in the s-wave and large N approximation. Black holes of the maximal mass
are in equilibrium. Unexpectedly, we find that nearly maximal quantum
Schwarzschild-de Sitter black holes anti-evaporate. However, there is a
different perturbative mode that leads to evaporation. We show that this mode
will always be excited when a pair of cosmological holes nucleates.Comment: 16 pages, LaTeX2e; submitted to Phys. Rev.
Model of black hole evolution
From the postulate that a black hole can be replaced by a boundary on the
apparent horizon with suitable boundary conditions, an unconventional scenario
for the evolution emerges. Only an insignificant fraction of energy of order
is radiated out. The outgoing wave carries a very small part of the
quantum mechanical information of the collapsed body, the bulk of the
information remaining in the final stable black hole geometry.Comment: 9 pages, harvmac, 3 figures, minor addition
Critical energy flux and mass in solvable theories of 2d dilaton gravity
In this paper we address the issue of determining the semiclassical threshold
for black hole formation in the context of a one-parameter family of theories
which continuously interpolates between the RST and BPP models. We find that
the results depend significantly on the initial static configuration of the
spacetime geometry before the influx of matter is turned on. In some cases
there is a critical energy density, given by the Hawking rate of evaporation,
as well as a critical mass (eventually vanishing). In others there is
neither nor a critical flux.Comment: LaTeX file, 12 pages, 4 figure
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