6,746 research outputs found
On the dimensional dependence of duality groups for massive p-forms
We study the soldering formalism in the context of abelian p-form theories.
We develop further the fusion process of massless antisymmetric tensors of
different ranks into a massive p-form and establish its duality properties. To
illustrate the formalism we consider two situations. First the soldering mass
generation mechanism is compared with the Higgs and Julia-Toulouse mechanisms
for mass generation due to condensation of electric and magnetic topological
defects. We show that the soldering mechanism interpolates between them for
even dimensional spacetimes, in this way confirming the Higgs/Julia-Toulouse
duality proposed by Quevedo and Trugenberger \cite{QT} a few years ago. Next,
soldering is applied to the study of duality group classification of the
massive forms. We show a dichotomy controlled by the parity of the operator
defining the symplectic structure of the theory and find their explicit
actions.Comment: Reference [8] has been properly place
On duality of the noncommutative extension of the Maxwell-Chern-Simons model
We study issues of duality in 3D field theory models over a canonical
noncommutative spacetime and obtain the noncommutative extension of the
Self-Dual model induced by the Seiberg-Witten map. We apply the dual projection
technique to uncover some properties of the noncommutative Maxwell-Chern-Simons
theory up to first-order in the noncommutative parameter. A duality between
this theory and a model similar to the ordinary self-dual model is
estabilished. The correspondence of the basic fields is obtained and the
equivalence of algebras and equations of motion are directly verified. We also
comment on previous results in this subject.Comment: Revtex, 9 pages, accepted for publication PL
Quantum Effects in the Spacetime of a Magnetic Flux Cosmic String
In this work we compute the vacuum expectation values of the energy-momentum
tensor and the average value of a massive, charged scalar field in the presence
of a magnetic flux cosmic string for both zero- and finite-temperature cases.Comment: To appear in the Int. Journal of Modern Phys. A (special issue).
Proceedings of the Second International Londrina Winter School on
Mathematical Methods in Physics, Londrina, Brazil, August 200
Contributions from Dilatonic Strings to the Flat Behaviour of the Rotational Curves in Galaxies
We analyse the flat behaviour of the rotational curves in some galaxies in
the framework of a dilatonic, current-carrying string. We determine the
expression of the tangential velocity of test objects following a stable
circular equatorial orbit in this spacetime.Comment: This version to be published in the Int. Journal of Modern Phys.
Massive scalar field near a cosmic string
The function of a massive scalar field near a cosmic string is
computed and then employed to find the vacuum fluctuation of the field. The
vacuum expectation value of the energy-momentum tensor is also computed using a
point-splitting approach. The obtained results could be useful also for the
case of self-interacting scalar fields and for the finite-temperature Rindler
space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte
A nearly cylindrically symmetric source in the Brans-Dicke gravity as the generator of the rotational curves of the galaxies
Observation shows that the velocities of stars grow by approximately 2 to 3
orders of magnitude when the distances from the centers of the galaxies are in
the range of kpc to kpc, before they begin to tend to a constant
value. Up to know, the reason for this behavior is still a matter for debate.
In this work, we propose a model which adequately describes this unusual
behavior using a (nearly) cylindrical symmetrical solution in the framework of
a scalar-tensor-like (the Brans-Dicke model) theory of gravity.Comment: 24 pages, 4 figures, accepted for publication in Eur. Phys. J.
Group theory analysis of electrons and phonons in N-layer graphene systems
In this work we study the symmetry properties of electrons and phonons in
graphene systems as function of the number of layers. We derive the selection
rules for the electron-radiation and for the electron-phonon interactions at
all points in the Brillouin zone. By considering these selection rules, we
address the double resonance Raman scattering process. The monolayer and
bilayer graphene in the presence of an applied electric field are also
discussed.Comment: 8 pages, 6 figure
Carbon nanotube: a low-loss spin-current waveguide
We demonstrate with a quantum-mechanical approach that carbon nanotubes are
excellent spin-current waveguides and are able to carry information stored in a
precessing magnetic moment for long distances with very little dispersion and
with tunable degrees of attenuation. Pulsed magnetic excitations are predicted
to travel with the nanotube Fermi velocity and are able to induce similar
excitations in remote locations. Such an efficient way of transporting magnetic
information suggests that nanotubes are promising candidates for memory devices
with fast magnetization switchings
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