1,013 research outputs found
Duality Cascade and Oblique Phases in Non-Commutative Open String Theory
We investigate the complete phase diagram of the decoupled world-sheet theory
of (P,Q) strings. These theories include 1+1 dimensional super Yang-Mills
theory and non-commutative open string theory. We find that the system exhibits
a rich fractal phase structure, including a cascade of alternating
supergravity, gauge theory, and matrix string theory phases. The cascade
proceeds via a series of SL(2,Z) S-duality transformations, and depends
sensitively on P and Q. In particular, we find that the system may undergo
multiple Hagedorn-type transitions as the temperature is varied.Comment: 21 pages, 4 figures, references adde
A Note on Warped String Compactification
We give a short review of a large class of warped string geometries, obtained
via F-theory compactified on Calabi-Yau fourfolds, that upon reduction to 5
dimensions give consistent supersymmetric realizations of the RS
compactification scenario.Comment: 11 pages, 3 figures; v3 corrected spelling of Calab
2D Black Hole and Holographic Renormalization Group
In hep-th/0311177, the Large renormalization group (RG) flows of a
modified matrix quantum mechanics on a circle, capable of capturing effects of
nonsingets, were shown to have fixed points with negative specific heat. The
corresponding rescaling equation of the compactified matter field with respect
to the RG scale, identified with the Liouville direction, is used to extract
the two dimensional Euclidean black hole metric at the new type of fixed
points. Interpreting the large RG flows as flow velocities in holographic
RG in two dimensions, the flow equation of the matter field around the black
hole fixed point is shown to be of the same form as the radial evolution
equation of the appropriate bulk scalar coupled to 2D black hole.Comment: 21 page
Quantum Black Hole Evaporation
We investigate a recently proposed model for a full quantum description of
two-dimensional black hole evaporation, in which a reflecting boundary
condition is imposed in the strong coupling region. It is shown that in this
model each initial state is mapped to a well-defined asymptotic out-state,
provided one performs a certain projection in the gravitational zero mode
sector. We find that for an incoming localized energy pulse, the corresponding
out-going state contains approximately thermal radiation, in accordance with
semi-classical predictions. In addition, our model allows for certain acausal
strong coupling effects near the singularity, that give rise to corrections to
the Hawking spectrum and restore the coherence of the out-state. To an
asymptotic observer these corrections appear to originate from behind the
receding apparent horizon and start to influence the out-going state long
before the black hole has emitted most of its mass. Finally, by putting the
system in a finite box, we are able to derive some algebraic properties of the
scattering matrix and prove that the final state contains all initial
information.Comment: 37 pages (figs 2 and 3 included as uuencoded compressed tar file),
Latex, needs epsf.tex, PUPT-1395, IASSNS-HEP-93/25 (revised version has minor
corrections, one reference added
Entropic gravity, minimum temperature, and modified Newtonian dynamics
Verlinde's heuristic argument for the interpretation of the standard
Newtonian gravitational force as an entropic force is generalized by the
introduction of a minimum temperature (or maximum wave length) for the
microscopic degrees of freedom on the holographic screen. With the simplest
possible setup, the resulting gravitational acceleration felt by a test mass m
from a point mass M at a distance R is found to be of the form of the modified
Newtonian dynamics (MOND) as suggested by Milgrom. The corresponding MOND-type
acceleration constant is proportional to the minimum temperature, which can be
interpreted as the Unruh temperature of an emerging de-Sitter space. This
provides a possible explanation of the connection between local MOND-type
two-body systems and cosmology.Comment: 12 pages, v6: published versio
Black Hole Horizons and Complementarity
We investigate the effect of gravitational back-reaction on the black hole
evaporation process. The standard derivation of Hawking radiation is
re-examined and extended by including gravitational interactions between the
infalling matter and the outgoing radiation. We find that these interactions
lead to substantial effects. In particular, as seen by an outside observer,
they lead to a fast growing uncertainty in the position of the infalling matter
as it approaches the horizon. We argue that this result supports the idea of
black hole complementarity, which states that, in the description of the black
hole system appropriate to outside observers, the region behind the horizon
does not establish itself as a classical region of space-time. We also give a
new formulation of this complementarity principle, which does not make any
specific reference to the location of the black hole horizon.Comment: Some minor modifications in text and the title chang
On RG-flow and the Cosmological Constant
The AdS/CFT correspondence implies that the effective action of certain
strongly coupled large gauge theories satisfy the Hamilton-Jacobi equation
of 5d gravity. Using an analogy with the relativistic point particle, I
construct a low energy effective action that includes the Einstein action and
obeys a Callan-Symanzik-type RG-flow equation. It follows from the flow
equation that under quite general conditions the Einstein equations admit a
flat space-time solution, but other solutions with non-zero cosmological
constant are also allowed. I discuss the geometric interpretation of this
result in the context of warped compactifications.Comment: 11 pages, 1 figure, contribution to the proceedings of Strings '99,
misprint correcte
Loop and surface operators in N=2 gauge theory and Liouville modular geometry
Recently, a duality between Liouville theory and four dimensional N=2 gauge
theory has been uncovered by some of the authors. We consider the role of
extended objects in gauge theory, surface operators and line operators, under
this correspondence. We map such objects to specific operators in Liouville
theory. We employ this connection to compute the expectation value of general
supersymmetric 't Hooft-Wilson line operators in a variety of N=2 gauge
theories.Comment: 60 pages, 11 figures; v3: further minor corrections, published
versio
Topological Dilatonic Supergravity Theories
We present a central extension of the super-Poincar\'e algebra in two
dimensions. Besides the usual Poincar\'e generators and the
supersymmetry generators we have Grassmann generators, a bosonic
internal symmetry generator and a central charge. We then build up the
topological gauge theory associated to this algebra. We can solve the classical
field equations for the fields which do not belong to the supergravity
multiplet and to a Lagrange multiplier multiplet. The resulting topological
supergravity theory turns out to be non-local in the fermionic sector.Comment: 11 pages, plain TeX, IFUSP-P/112
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