7,637 research outputs found
Theta Dependence In The Large N Limit Of Four-Dimensional Gauge Theories
The theta dependent of pure gauge theories in four dimensions can be studied
using a duality of large N gauge theories with string theory on a certain
spacetime. Via this duality, one can argue that for every theta, there are
infinitely many vacua that are stable in the large N limit. The true vacuum,
found by minimizing the energy in this family, is a smooth function of theta
except at theta equal to pi, where it jumps. This jump is associated with
spontaneous breaking of CP symmetry. Domain walls separating adjacent vacua are
described in terms of wrapped sixbranes.Comment: 8 p
Wu-Yang Monopoles and Non-Abelian Seiberg-Witten Equations
Some exact solutions of the SU(2) Seiberg-Witten equations in Minkowski
spacetime are given.Comment: 6 pages, LATEX file, no figures. To appear in Mod. Phys. Lett.
Asymptotically AdS Magnetic Branes in (n+1)-dimensional Dilaton Gravity
We present a new class of asymptotically AdS magnetic solutions in
()-dimensional dilaton gravity in the presence of an appropriate
combination of three Liouville-type potentials. This class of solutions is
asymptotically AdS in six and higher dimensions and yields a spacetime with
longitudinal magnetic field generated by a static brane. These solutions have
no curvature singularity and no horizons but have a conic geometry with a
deficit angle. We find that the brane tension depends on the dilaton field and
approaches a constant as the coupling constant of dilaton field goes to
infinity. We generalize this class of solutions to the case of spinning
magnetic solutions and find that, when one or more rotation parameters are
nonzero, the brane has a net electric charge which is proportional to the
magnitude of the rotation parameters. Finally, we use the counterterm method
inspired by AdS/CFT correspondence and compute the conserved quantities of
these spacetimes. We found that the conserved quantities do not depend on the
dilaton field, which is evident from the fact that the dilaton field vanishes
on the boundary at infinity.Comment: 15 page
Gravitational Backreaction Effects on the Holographic Phase Transition
We study radion stabilization in the compact Randall-Sundrum model by
introducing a bulk scalar field, as in the Goldberger and Wise mechanism, but
(partially) taking into account the backreactions from the scalar field on the
metric. Our generalization reconciles the radion potential found by Goldberger
and Wise with the radion mass obtained with the so-called superpotential method
where backreaction is fully considered. Moreover we study the holographic phase
transition and its gravitational wave signals in this model. The improved
control over backreactions opens up a large region in parameter space and
leads, compared to former analysis, to weaker constraints on the rank N of the
dual gauge theory. We conclude that, in the regime where the 1/N expansion is
justified, the gravitational wave signal is detectable by LISA.Comment: 42 pages, 4 figures; v2: minor changes for the publicatio
Evidence for fast thermalization in the plane-wave matrix model
We perform a numerical simulation of the classical evolution of the
plane-wave matrix model with semiclassical initial conditions. Some of these
initial conditions thermalize and are dual to a black hole forming from the
collision of D-branes in the plane wave geometry. In particular, we consider a
large fuzzy sphere (a D2-brane) plus a single eigenvalue (a D0-particle) going
exactly through the center of the fuzzy sphere and aimed to intersect it.
Including quantum fluctuations of the off-diagonal modes in the initial
conditions, with sufficient kinetic energy the configuration collapses to a
small size. We also find evidence for fast thermalization: rapidly decaying
autocorrelation functions at late times with respect to the natural time scale
of the system.Comment: 5 pages, 5 figures, revtex4 format; v2: minor typos fixed; v3: 8
pages, 9 figures, minor changes, includes a supplement as appeared on PR
Bound states in N = 4 SYM on T^3: Spin(2n) and the exceptional groups
The low energy spectrum of (3+1)-dimensional N=4 supersymmetric Yang-Mills
theory on a spatial three-torus contains a certain number of bound states,
characterized by their discrete abelian magnetic and electric 't Hooft fluxes.
At weak coupling, the wave-functions of these states are supported near points
in the moduli space of flat connections where the unbroken gauge group is
semi-simple. The number of such states is related to the number of normalizable
bound states at threshold in the supersymmetric matrix quantum mechanics with
16 supercharges based on this unbroken group. Mathematically, the determination
of the spectrum relies on the classification of almost commuting triples with
semi-simple centralizers. We complete the work begun in a previous paper, by
computing the spectrum of bound states in theories based on the
even-dimensional spin groups and the exceptional groups. The results satisfy
the constraints of S-duality in a rather non-trivial way.Comment: 20 page
Witten-Veneziano from Green-Schwarz
We consider the U(1) problem within the AdS/CFT framework. We explain how the
Witten-Veneziano formula for the eta' mass is related to a generalized
Green-Schwarz mechanism. The closed string mode, that cancels the anomaly of
the gauged U(1) axial symmetry, is identified with the eta' meson. In a
particular set-up of D3-branes on a C3/(Z3xZ3) orbifold singularity, the eta'
meson is a twisted-sector R-R field.Comment: 10 pages, LaTex. 1 eps figure. v2: minor changes, refs. added, to
appear in JHE
On Induced Gravity in 2-d Topological Theories
We study 2-d gauge theories with the objective to understand, also
at the quantum level, the emergence of induced gravity. The wave functionals -
representing the eigenstates of a vanishing flat potential - are obtained in
the representation. The composition of the space they describe is then
analyzed: the state corresponding to the singlet representation of the gauge
group describes a topological universe. For other representations a metric
which is invariant under the residual gauge group is induced, apart from
possible topological obstructions. Being inherited from the group metric it is
rather rigid.Comment: 38, tex, 160/93/e
Non-abelian gauge antisymmetric tensor fields
We construct the theory of non-abelian gauge antisymmetric tensor fields,
which generalize the standard Yang-MIlls fields and abelian gauge p-forms. The
corresponding gauge group acts on the space of inhomogeneous differential forms
and it is shown to be a supergroup. The wide class of generalized Chern-Simons
actions is constructed.Comment: 20 pages, Late
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