1,844 research outputs found

### Black hole information, unitarity, and nonlocality

The black hole information paradox apparently indicates the need for a
fundamentally new ingredient in physics. The leading contender is nonlocality.
Possible mechanisms for the nonlocality needed to restore unitarity to black
hole evolution are investigated. Suggestions that such dynamics arises from
ultra-planckian modes in Hawking's derivation are investigated and found not to
be relevant, in a picture using smooth slices spanning the exterior and
interior of the horizon. However, no simultaneous description of modes that
have fallen into the black hole and outgoing Hawking modes can be given without
appearance of a large kinematic invariant, or other dependence on
ultra-planckian physics; a reliable argument for information loss thus has not
been constructed. This suggests that strong gravitational dynamics is
important. Such dynamics has been argued to be fundamentally nonlocal in
extreme situations, such as those required to investigate the fate of
information.Comment: 34 pages, 4 figures. Major revision of hep-th/0604047. v2: minor
corrections and added referenc

### Locality in quantum gravity and string theory

Breakdown of local physics in string theory at distances longer than the
string scale is investigated. Such nonlocality would be expected to be visible
in ultrahigh-energy scattering. The results of various approaches to such
scattering are collected and examined. No evidence is found for non-locality
from strings whose length grows linearly with the energy. However, local
quantum field theory does apparently fail at scales determined by gravitational
physics, particularly strong gravitational dynamics. This amplifies locality
bound arguments that such failure of locality is a fundamental aspect of
physics. This kind of nonlocality could be a central element of a possible
loophole in the argument for information loss in black holes.Comment: 26 pages, 3 figures, harvmac. v2: minor changes to bring into accord
with revised paper hep-th/060519

### High energy QCD scattering, the shape of gravity on an IR brane, and the Froissart bound

High-energy scattering in non-conformal gauge theories is investigated using
the AdS/CFT dual string/gravity theory. It is argued that strong-gravity
processes, such as black hole formation, play an important role in the dual
dynamics. Further information about this dynamics is found by performing a
linearized analysis of gravity for a mass near an infrared brane; this gives
the far field approximation to black hole or other strong-gravity effects, and
in particular allows us to estimate their shape. From this shape, one can infer
a total scattering cross-section that grows with center of mass energy as ln^2
E, saturating the Froissart bound.Comment: 27 pages, 1 fig, harvmac. v2: references added, typos corrected v3:
typo correcte

### Nonlocality vs. complementarity: a conservative approach to the information problem

A proposal for resolution of the information paradox is that "nice slice"
states, which have been viewed as providing a sharp argument for information
loss, do not in fact do so as they do not give a fully accurate description of
the quantum state of a black hole. This however leaves an information
*problem*, which is to provide a consistent description of how information
escapes when a black hole evaporates. While a rather extreme form of
nonlocality has been advocated in the form of complementarity, this paper
argues that is not necessary, and more modest nonlocality could solve the
information problem. One possible distinguishing characteristic of scenarios is
the information retention time. The question of whether such nonlocality
implies acausality, and particularly inconsistency, is briefly addressed. The
need for such nonlocality, and its apparent tension with our empirical
observations of local quantum field theory, may be a critical missing piece in
understanding the principles of quantum gravity.Comment: 11 pages of text and figures, + references. v2 minor text. v3 small
revisions to match final journal versio

### Linearized Gravity in Brane Backgrounds

A treatment of linearized gravity is given in the Randall-Sundrum background.
The graviton propagator is found in terms of the scalar propagator, for which
an explicit integral expression is provided. This reduces to the
four-dimensional propagator at long distances along the brane, and provides
estimates of subleading corrections. Asymptotics of the propagator off the
brane yields exponential falloff of gravitational fields due to matter on the
brane. This implies that black holes bound to the brane have a "pancake"-like
shape in the extra dimension, and indicates validity of a perturbative
treatment off the brane. Some connections with the AdS/CFT correspondence are
described.Comment: 31 pages, harvmac. v2: minor typo and reference corrections. v3:
minor corrections to eqs and discussio

### Gauge/String-Gravity Duality and Froissart Bound

The gauge/string-gravity duality correspondence opened renewed hope and
possibility to address some of the fundamental and non-perturbative QCD
problems in particle physics, such as hadron spectrum and Regge behavior of the
scattering amplitude at high energies. One of the most fundamental and
long-standing problem is the high energy behavior of total cross-sections.
According to a series of exhaustive tests by the COMPETE group, (1). total
cross-sections have a universal Heisenberg behavior in energy corresponding to
the maximal energy behavior allowed by the Froissart bound, i.e., $A + B ln^2
(s/s_0)$ with $B \sim 0.32 mb$ and $s_0 \sim 34.41 GeV^2$ for all reactions,
and (2). the factorization relation among $\sigma_{pp, even}, \sigma_{\gamma
p}, and \sigma_{\gamma \gamma}$ is well satisfied by experiments. I discuss the
recent interesting application of the gauge/string-gravity duality of $AdS/CFT$
correspondence with a deformed background metric so as to break the conformal
symmetry that can lead to the Heisenberg behavior of rising total
cross-sections, and present some preliminary results on the high energy QCD
from Planckian scattering in $AdS$ and black-hole production.Comment: 10 pages, Presented to the Coral Gables Conference 2003, Launching of
BelleE\'poque in High Energy Physics and Cosmology, 17 - 21 December 2003,
Fort Lauderdale, Florid

### Precursors, black holes, and a locality bound

We revisit the problem of precursors in the AdS/CFT correspondence.
Identification of the precursors is expected to improve our understanding of
the tension between holography and bulk locality and of the resolution of the
black hole information paradox. Previous arguments that the precursors are
large, undecorated Wilson loops are found to be flawed. We argue that the role
of precursors should become evident when one saturates a certain locality
bound. The spacetime uncertainty principle is a direct consequence of this
bound.Comment: 26 pages, 8 figs; reference added, minor clarification in sec. 2;
incorrect draft mistakenly used in version

### Bulk shape of brane-world black holes

We propose a method to extend into the bulk asymptotically flat static
spherically symmetric brane-world metrics. We employ the multipole (1/r)
expansion in order to allow exact integration of the relevant equations along
the (fifth) extra coordinate and make contact with the parameterized
post-Newtonian formalism. We apply our method to three families of solutions
previously appeared as candidates of black holes in the brane world and show
that the shape of the horizon is very likely a flat ``pancake'' for
astrophysical sources.Comment: 10 pages, MPLA style, 5 figures, accepted for publication in MPL

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