2,648 research outputs found
Finite Heisenberg Groups in Quiver Gauge Theories
We show by direct construction that a large class of quiver gauge theories
admits actions of finite Heisenberg groups. We consider various quiver gauge
theories that arise as AdS/CFT duals of orbifolds of C^3, the conifold and its
orbifolds and some orbifolds of the cone over Y(p,q). Matching the gauge theory
analysis with string theory on the corresponding spaces implies that the
operators counting wrapped branes do not commute in the presence of flux.Comment: 25 pages, 13 figure
A new, efficient algorithm for the Forest Fire Model
The Drossel-Schwabl Forest Fire Model is one of the best studied models of
non-conservative self-organised criticality. However, using a new algorithm,
which allows us to study the model on large statistical and spatial scales, it
has been shown to lack simple scaling. We thereby show that the considered
model is not critical. This paper presents the algorithm and its parallel
implementation in detail, together with large scale numerical results for
several observables. The algorithm can easily be adapted to related problems
such as percolation.Comment: 38 pages, 28 figures, REVTeX 4, RMP style; V2 is for clarifications
as well as corrections and update of reference
The Entropy Bound for Local Quantum Field Theory
We investigate the entropy bound for local quantum field theory in this
paper. Both the bosonic and fermionic fields confined to an asymptotically flat
spacetime are examined. By imposing the non-gravitational collapse condition,
we find both of them are limited by the same entropy bound , where
is the boundary area of the region where the quantum fields are contained in.
The gap between this entropy bound and the holographic entropy has been
verified.Comment: Revtex, 4 page, title changed, the published versio
Static Electric Dipole Polarizabilities of Na Clusters
The static electric dipole polarizability of clusters with
even N has been calculated in a collective, axially averaged and a
three-dimensional, finite-field approach for , including the
ionic structure of the clusters. The validity of a collective model for the
static response of small systems is demonstrated. Our density functional
calculations verify the trends and fine structure seen in a recent experiment.
A pseudopotential that reproduces the experimental bulk bond length and atomic
energy levels leads to a substantial increase in the calculated
polarizabilities, in better agreement with experiment. We relate remaining
differences in the magnitude of the theoretical and experimental
polarizabilities to the finite temperature present in the experiments.Comment: 7 pages, 3 figures, accepted for publication in the European Physical
Journal
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