1,556 research outputs found
Wilson loops in large N field theories
We propose a method to calculate the expectation values of an operator
similar to the Wilson loop in the large N limit of field theories. We consider
N=4 3+1 dimensional super-Yang-Mills. The prescription involves calculating the
area of a fundamental string worldsheet in certain supergravity backgrounds. We
also consider the case of coincident M-theory fivebranes where one is lead to
calculating the area of M-theory two-branes. We briefly discuss the computation
for 2+1 dimensional super-Yang-Mills with sixteen supercharges which is
non-conformal. In all these cases we calculate the energy of quark-antiquark
pair.Comment: 12 pages, harvmac. v2: sign in eqn. (5.6) corrected, v3 typo
correcte
Holographic description of D3-branes in flat space
We describe a scheme for constructing the holographic dual of the full
D3-brane geometry with charge by embedding it into a large anti-de Sitter
space of size . Such a geometry is realized in a multi-center anti-de Sitter
geometry which admits a simple field theory interpretation as gauge
theory broken to . We find that the characteristic size of
the D3-brane geometry is of order where is the scale of
the Higgs. By choosing to be much larger than , the scale of the
D3-brane metric can be well separated from the Higgs scale in the radial
coordinate. We generalize the holographic energy-distance relation and estimate
the characteristic energy scale associated with these radial scales, and find
that the relation becomes effectively independent in the range
. This implies that all detailed structure of the
D3-brane geometry is encoded in the fine structure of the boundary gauge theory
at around the Higgs scale.Comment: 8 pages, 1 eps figur
The gauge-string duality and heavy ion collisions
I review at a non-technical level the use of the gauge-string duality to
study aspects of heavy ion collisions, with special emphasis on the trailing
string calculation of heavy quark energy loss. I include some brief
speculations on how variants of the trailing string construction could provide
a toy model of black hole formation and evaporation. This essay is an invited
contribution to "Forty Years of String Theory" and is aimed at philosophers and
historians of science as well as physicists.Comment: 21 page
The Gregory-Laflamme instability for the D2-D0 bound state
The D2-D0 bound state exhibits a Gregory-Laflamme instability when it is
sufficiently non-extremal. If there are no D0-branes, the requisite
non-extremality is finite. When most of the extremal mass comes from D0-branes,
the requisite non-extremality is very small. The location of the threshhold for
the instability is determined using a local thermodynamic analysis which is
then checked against a numerical analysis of the linearized equations of
motion. The thermodynamic analysis reveals an instability of non-commutative
field theory at finite temperature, which may occur only at very long
wavelengths as the decoupling limit is approached.Comment: 19 pages, Latex2e. v2: two refs added. v3: clearer exposition in
section
Non-supersymmetric deformations of the dual of a confining gauge theory
We introduce a computational technique for studying non-supersymmetric
deformations of domain wall solutions of interest in AdS/CFT. We focus on the
Klebanov-Strassler solution, which is dual to a confining gauge theory. From an
analysis of asymptotics we find that there are three deformations that leave
the ten-dimensional supergravity solution regular and preserve the global
bosonic symmetries of the supersymmetric solution. Also, we show that there are
no regular near-extremal deformations preserving the global symmetries, as one
might expect from the existence of a gap in the gauge theory.Comment: 18 pages, latex, published as JHEP 0305 (2003) 03
Exact Absorption Probability in the Extremal Six-Dimensional Dyonic String Background
We show that the minimally coupled massless scalar wave equation in the
background of an six-dimensional extremal dyonic string (or D1-D5 brane
intersection) is exactly solvable, in terms of Mathieu functions. Using this
fact, we calculate absorption probabilities for these scalar waves, and present
the explicit results for the first few low energy corrections to the
leading-order expressions. For a specific tuning of the dyonic charges one can
reach a domain where the low energy absorption probability goes to zero with
inverse powers of the logarithm of the energy. This is a dividing domain
between the regime where the low energy absorption probability approaches zero
with positive powers of energy and the regime where the probability is an
oscillatory function of the logarithm of the energy. By the conjectured AdS/CFT
correspondence, these results shed novel light on the strongly coupled
two-dimensional field theory away from its infrared conformally invariant fixed
point (the strongly coupled ``non-critical'' string).Comment: Latex (3 times), 23 page
Cosmology with a dynamically screened scalar interaction in the dark sector
Motivated in part by string theory, we consider a modification of the
LambdaCDM cosmological model in which the dark matter has a long-range scalar
force screened by light particles. Scalar forces can have interesting effects
on structure formation: the main example presented here is the expulsion of
dark matter halos from low density regions, or voids, in the galaxy
distribution.Comment: 26 pages, 3 figure
Greybody factor for D3-branes in B field
We calculate the effect of noncommutative spacetime on the greybody factor on
the supergravity side. For this purpose we introduce a system of D3-branes with
a constant NS -field along their world volume directions ().
Considering the propagation of minimally coupled scalar with non-zero momentum
along(), we derive an exact form of the greybody factor in field.
It turns out that . This means that the
presence of -field (the noncommutativity) suppresses the potential barrier
surrounding the black hole. As a result, it comes out the increase of greybody
factor.Comment: some discussions and references are added, 10 pages, no figure,
ReVTe
On the construction of local fields in the bulk of AdS_5 and other spaces
In the Poincare patch of Minkovski AdS_5 we explicitly construct local bulk
fields from the boundary operators, to leading order in 1/N. We also construct
the Green's function implicitly defined by this procedure. We generalize the
construction of local fields for near horizon geometries of Dp branes. We try
to expand the procedure to the interacting case, with partial success.Comment: 11 pages, LaTe
On (multi-)center branes and exact string vacua
Multicenter supergravity solutions corresponding to Higgs phases of
supersymmetric Yang-Mills theories are considered. For NS5 branes we identify
three cases where there is a description in terms of exact conformal field
theories. Other supergravity solutions, such as D3-branes with angular
momentum, are understood as special limits of multicenter ones. Within our
context we also consider 4-dim gravitational multi-instantons.Comment: 9 pages, latex; To be published in the proceedings of the Quantum
Aspects of Gauge Theories, Supersymmetry and Unification, Corfu, Greece,
20-26 September 199
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