1,058 research outputs found
Some Interesting Properties of Field theories with an Infinite Number of Fields
We give an indication that gravity coupled to an infinite number of fields
might be a renormalizable theory. A toy model with an infinite number of
interacting fermions in four-dimentional space-time is analyzed. The model is
finite at any order in perturbation theory. However, perturbation theory is
valid only for external momenta smaller than , where
is the coupling constant.Comment: 12 pages, LaTe
Information Loss in Quantum Gravity Without Black Holes
We use the weak field approximation to show that information is lost in
principle in quantum gravity.Comment: 14pp, Late
On the M-Theory Approach to (Compactified) 5D Field Theories
We construct M-theory curves associated with brane configurations of SU(N),
SO(N) and 5d supersymmetric gauge theories compactified on a circle.
From the curves we can account for all the existing different SU(N) field
theories with . This is the correct bound for . We
remark on the exceptional case SU(2). The bounds obtained for SO(N) and
are and , respectively.Comment: 18 pages, minor correction
Wilson Loops in the Large N Limit at Finite Temperature
Using a proposal of Maldacena we compute in the framework of the supergravity
description of N coincident D3 branes the energy of a quark anti-quark pair in
the large N limit of U(N) N=4 SYM in four dimensions at finite temperature.Comment: 7 pages, LaTeX2e, 5 eps figures; references added and corrected,
typos correcte
Black Hole Horizon Fluctuations
It is generally admitted that gravitational interactions become large at an
invariant distance of order from the black hole horizon. We show that due
to the ``atmosphere'' of high angular particles near the horizon strong
gravitational interactions already occur at an invariant distance of the order
of . The implications of these results for the origin of black
hole radiation, the meaning of black hole entropy and the information puzzle
are discussed.Comment: Latex, 22 pages (minor corrections and precisions added
Free Energies and Probe Actions for Near-horizon D-branes and D1 + D5 System
By working with the free energy for the type II supergravity near-horizon
solution of N coincident non-extremal Dp-branes we study the transitions among
the non-conformal Dp-brane system, the perturbative super Yang-Mills theory and
a certain system associated with M theory. We derive a relation between this
free energy and the action of a Dp-brane probe in the N Dp-brane background.
Constructing the free energy for the five dimensional black hole labeled by the
D1-brane and D5-brane charges we find the similar relation between it and the
action of a D1 or D5 brane probe in the D1 + D5 brane background. These
relations are explained by the massive open strings stretched between the
relevant D-branesComment: 14 pages, LaTeX2e, no figure
Stringy effect of the holographic correspondence for Dp-brane backgrounds
Based on the holographic conjecture for superstrings on Dp-brane backgrounds
and the dual (p+1)-dimensional gauge theory () given in
hep-th/0308024 and hep-th/0405203, we continue the study of superstring
amplitudes including string higher modes (). We give a prediction to
the two-point functions of operators with large R-charge J. The effect of
stringy modes do not appear as the form of anomalous dimensions except for p=3.
Instead, it gives non-trivial correction to the two-point functions for
supergravity modes. For p=4, the scalar two-point functions for any n behave
like free fields of the effective dimension d_{eff}=6 in the infra-red limit.Comment: 23 pages, typos correcte
Inflection Point Inflation and Time Dependent Potentials in String Theory
We consider models of inflection point inflation. The main drawback of such
models is that they suffer from the overshoot problem. Namely the initial
condition should be fine tuned to be near the inflection point for the universe
to inflate. We show that stringy realizations of inflection point inflation are
common and offer a natural resolution to the overshoot problem.Comment: 15 pages, 2 figures, refs. adde
- âŠ