8,089 research outputs found
Coleman-Weinberg Mechanism and Interaction of D3-Branes in Type 0 String Theory
The low-energy theory on the world volume of parallel static D3-branes of
type 0 strings is the Yang-Mills theory with six scalar fields in the adjoint
representation. One-loop corrections in this theory induce Coleman-Weinberg
effective potential, which can be interpreted as an interaction energy of
D3-branes. The potential is repulsive at short distances and attractive at
large ones. In the equilibrium, a large number of D3-branes forms a spherical
shell with the radius proportional to the characteristic energy scale of the
world-volume theory.Comment: 5 pages, LaTex, 1 figure; v2: Discussion of the interaction potential
between D3-branes at short distances is modified, version to be published in
Phys. Lett.
Holographic Renormalisation and the Electroweak Precision Parameters
We study the effects of holographic renormalisation on an AdS/QCD inspired
description of dynamical electroweak symmetry breaking. Our model is a 5D slice
of AdS_5 geometry containing a bulk scalar and SU(2) times SU(2) gauge fields.
The scalar field obtains a VEV which represents a condensate that triggers
electroweak symmetry breaking. Fermion fields are constrained to live on the UV
brane and do not propagate in the bulk. The two-point functions are
holographically renormalised through the addition of boundary counterterms.
Measurable quantities are then expressed in terms of well defined physical
parameters, free from any spurious dependence on the UV cut-off. A complete
study of the precision parameters is carried out and bounds on physical
quantities derived. The large-N scaling of results is discussed
Viscosity of gauge theory plasma with a chemical potential from AdS/CFT correspondence
We compute the strong coupling limit of the shear viscosity for the N=4
super-Yang-Mill theory with a chemical potential. We use the five-dimensional
Reissner-Nordstrom-anti-deSitter black hole, so the chemical potential is the
one for the R-charges U(1)_R^3. We compute the quasinormal frequencies of the
gravitational and electromagnetic vector perturbations in the background
numerically. This enables one to explicitly locate the diffusion pole for the
shear viscosity. The ratio of the shear viscosity eta to the entropy density s
is eta/s=1/(4pi) within numerical errors, which is the same result as the one
without chemical potential.Comment: 11 pages, 5 figures, ReVTeX4; v2: minor improvements; v3:
explanations added and improved; v4: version to appear in PR
On the Problems with Background Independence in String Theory
The problems with background independence are discussed in the example of
open string theory. Based on the recent proposal by Witten I calculate the
String Field Theory action in conformal perturbation theory to second order and
demonstrate that the proper treatment of contact terms leads to nontrivial
equations of motion. I conjecture the form of the field theory action to all
orders.Comment: 15p., Preprint IASSNS-HEP-93/6
Distortion of Schwarzschild-anti-de Sitter black holes to black strings
Motivated by the existence of black holes with various topologies in
four-dimensional spacetimes with a negative cosmological constant, we study
axisymmetric static solutions describing any large distortions of
Schwarzschild-anti-de Sitter black holes parametrized by the mass . Under
the approximation such that is much larger than the anti-de Sitter radius,
it is found that a cylindrically symmetric black string is obtained as a
special limit of distorted spherical black holes. Such a prolonged distortion
of the event horizon connecting a Schwarzschild-anti-de Sitter black hole to a
black string is allowed without violating both the usual black hole
thermodynamics and the hoop conjecture for the horizon circumference.Comment: 13 pages, accepted for publication in Physical Review
Holography and Rotating AdS Black Holes
We probe the AdS/CFT correspondence by comparing the thermodynamics of a
rotating black hole in five-dimensional anti-de Sitter space with that of a
conformal field theory on , whose parameters come from the boundary of
spacetime. In the high temperature limit, we find agreement between gauge
theory and gravity in all thermodynamic quantities upto the same factor of 4/3
that appears for nonrotating holes.Comment: LaTeX, 13 pages, typos corrected, references adde
Heavy Quark Potential from Gauge/Gravity Duality: A Large D Analysis
The heavy-quark potential is calculated in the framework of gauge/gravity
duality using the large-D approximation, where D is the number of dimensions
transverse to the flux tube connecting a quark and an antiquark in a flat
D+2-dimensional spacetime. We find that in the large-D limit the leading
correction to the ground-state energy, as given by an effective Nambu-Goto
string, arises not from the heavy modes but from the behavior of the massless
modes in the vicinity of the quark and the antiquark. We estimate this
correction and find that it should be visible in the near-future lattice QCD
calculations of the heavy-quark potential.Comment: 22 pages, 5 Figures. v2: references added, typos corrected and, Sec.
4 rewritten with an expanded non-perturbative discussion of the corrections
to the Arvis potential arising from the massless modes near the boundary of
the qcd strin
A Superstring Theory in Four Curved Space-Time Dimensions
Neveu-Schwarz-Ramond type heterotic and type-II superstrings in four
dimensional curved space-time are constructed as exact superconformal
theories. The tachyon is eliminated with a GSO projection. The theory is based
on the N=1 superconformal gauged WZW model for the anti-de Sitter coset
with integer central extension . The model has dynamical
duality properties in its space-time metric that are similar to the large-small
() duality of tori. To first order in a expansion we
give expressions for the metric, the dilaton, the Ricci tensor and their dual
generalizations. The curvature scalar has several singularities at various
locations in the 4-dimensional manifold. This provides a new singular solution
to Einstein's equations in the presence of matter in four dimensions. A
non-trivial path integral measure which we conjectured in previous work for
gauged WZW models is verified.Comment: 12 page
MQCD, ('Barely') G_2 Manifolds and (Orientifold of) a Compact Calabi-Yau
We begin with a discussion on two apparently disconnected topics - one
related to nonperturbative superpotential generated from wrapping an M2-brane
around a supersymmetric three cycle embedded in a G_2-manifold evaluated by the
path-integral inside a path-integral approach of [1], and the other centered
around the compact Calabi-Yau CY_3(3,243) expressed as a blow-up of a degree-24
Fermat hypersurface in WCP^4[1,1,2,8,12]. For the former, we compare the
results with the ones of Witten on heterotic world-sheet instantons [2]. The
subtopics covered in the latter include an N=1 triality between Heterotic, M-
and F-theories, evaluation of RP^2-instanton superpotential, Picard-Fuchs
equation for the mirror Landau-Ginsburg model corresponding to CY_3(3,243),
D=11 supergravity corresponding to M-theory compactified on a `barely' G_2
manifold involving CY_3(3,243) and a conjecture related to the action of
antiholomorphic involution on period integrals. We then show an indirect
connection between the two topics by showing a connection between each one of
the two and Witten's MQCD [3]. As an aside, we show that in the limit of
vanishing "\zeta", a complex constant that appears in the Riemann surfaces
relevant to definining the boundary conditions for the domain wall in MQCD, the
infinite series of [4] used to represent a suitable embedding of a
supersymmetric 3-cycle in a G_2-mannifold, can be summed.Comment: 37 pages, LaTex; PARTLY based on talks given at ``Seventh Workshop on
QCD" [session on "Strings, Branes and (De-)Construction"], Jan 6-10, 2003, La
Cittadelle, Villefranche-sur-Mer, France; Fourth Workshop on ``Gauge Fields
and Strings", Feb 25-Mar 1, 2003, Jena, Germany; ``XII Oporto Meeting on
Geometry, Topology and Strings", July 17-20, 2003, Oporto, Portugal; "SQS03"
- International Workshop on "Supersymmetries and Quantum Symmetries', July
24-29, 2003, JINR, Dubna, Russia; poster presented at ``XIV International
Congress on Mathematical Physics", July 28-Aug 2, 2003, Lisbon, Portuga
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