2,476 research outputs found
Covariant Quiver Gauge Theories
We consider dimensional reduction of gauge theories with arbitrary gauge
group in a formalism based on equivariant principal bundles. For the classical
gauge groups we clarify the relations between equivariant principal bundles and
quiver bundles, and show that the reduced quiver gauge theories are all
generically built on the same universal symmetry breaking pattern. The
formalism enables the dimensional reduction of Chern-Simons gauge theories in
arbitrary odd dimensionalities. The reduced model is a novel Chern-Simons-Higgs
theory consisting of a Chern-Simons term valued in the residual gauge group
plus a higher order gauge and diffeomorphism invariant coupling of Higgs fields
with the gauge fields. We study the moduli spaces of solutions, which in some
instances provide geometric representations of certain quiver varieties as
moduli spaces of flat invariant connections. As physical applications, we
consider dimensional reductions involving non-compact gauge supergroups as a
means for systematically inducing novel couplings between gravity and matter.
In particular, we reduce Chern-Simons supergravity to a quiver gauge theory of
AdS gravity involving a non-minimal coupling to scalar Higgs fermion fields.Comment: 32 pages; v2: minor corrections, reference adde
Topological gravity and transgression holography
We show that Poincare-invariant topological gravity in even dimensions can be
formulated as a transgression field theory in one higher dimension whose gauge
connections are associated to linear and nonlinear realizations of the Poincare
group ISO(d-1,1). The resulting theory is a gauged WZW model whereby the
transition functions relating gauge fields live in the coset
ISO(d-1,1)/SO(d-1,1). The coordinate parametrizing the coset space is
identified with the scalar field in the adjoint representation of the gauge
group of the even-dimensional topological gravity theory. The supersymmetric
extension leads to topological supergravity in two dimensions starting from a
transgression field theory which is invariant under the supersymmetric
extension of the Poincare group in three dimensions. We also apply this
construction to a three-dimensional Chern-Simons theory of gravity which is
invariant under the Maxwell algebra and obtain the corresponding WZW model.Comment: 22 pages; v2: minor corrections, references added; v3: analysis
involving Maxwell algebra expanded, references added; v4: referencing fixed;
Final version to be published in Physical Review
Propagation of localized surface plasmons in sets of metallic nanocylinders at the exit of subwavelength slits
We analyze, by means of numerical simulations, transmission enhancements
through sub- wavelength slits due to the presence of sets of plasmonic
nanocylinders, placed near the exit of these apertures. Further, we extend this
study to photonic crystals of dipolar plasmonic particles in front of an array
of extraordinarily transmitting slits practiced in a metallic slab.Comment: 20 pages, 9 figures. Submitted to Journal of Nanophotonic
Magnetic field evolution and equilibrium configurations in neutron star cores: the effect of ambipolar diffusion
As another step towards understanding the long-term evolution of the magnetic
field in neutron stars, we provide the first simulations of ambipolar diffusion
in a spherical star. Restricting ourselves to axial symmetry, we consider a
charged-particle fluid of protons and electrons carrying the magnetic flux
through a motionless, uniform background of neutrons that exerts a collisional
drag force on the former. We also ignore the possible impact of beta decays,
proton superconductivity, and neutron superfluidity. All initial magnetic field
configurations considered are found to evolve on the analytically expected
time-scales towards "barotropic equilibria" satisfying the "Grad-Shafranov
equation", in which the magnetic force is balanced by the degeneracy pressure
gradient, so ambipolar diffusion is choked. These equilibria are so-called
"twisted torus" configurations, which include poloidal and toroidal components,
the latter restricted to the toroidal volumes in which the poloidal field lines
close inside the star. In axial symmetry, they appear to be stable, although
they are likely to undergo non-axially symmetric instabilities.Comment: MNRAS, accepte
Liver preservation with lidoflazine and the university of wisconsin solution: A dose-finding study
Oxidized Forms of Antiaromatic Oligomers of Biphenylene
Rsumen de la comunicaciónThe importance of antiaromatic molecules in Chemistry and more recently in material science is rising. In the particular case of applications in electronics, the antiaromatic skeleton offers the favorable situation of high energy (i.e., destabilized) occupied molecular orbitals allowing to ease oxidation, doping or electron transfer to form conductive and photo-active substrates.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Biomass partitioning and gas exchange parameters in different Musa cultivars as influenced by natural shade
Poster presented at Tropentag 2011 Development on the Margin. Bonn (Germany), 3-7 Oct 2011
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