56,553 research outputs found
A monopole solution from noncommutative multi-instantons
We extend the relation between instanton and monopole solutions of the
selfduality equations in SU(2) gauge theory to noncommutative space-times.
Using this approach and starting from a noncommutative multi-instanton solution
we construct a U(2) monopole configuration which lives in 3 dimensional
ordinary space. This configuration resembles the Wu-Yang monopole and satisfies
the selfduality (Bogomol'nyi) equations for a U(2) Yang-Mills-Higgs system.Comment: 19 pages; title and abstract changed, brane interpretation corrected.
Version to appear in JHE
Gauge fields in a string-cigar braneworld
In this work we investigate the properties of an Abelian gauge vector field
in a thin and in a smoothed string-like braneworld, the so-called string-cigar
model. This thick brane scenario satisfies the regularity conditions and it can
be regarded as an interior and exterior string-like solution. The source
undergoes a geometric Ricci flow which is connected to a variation of the bulk
cosmological constant. The Ricci flow changes the width and amplitude of the
massless mode at the brane core and recover the usual thin string-like behavior
at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum
for both the thin brane and the string-cigar. It turns out that both models
exhibit a mass gap between the massless and the massive modes and between the
high and the low mass regimes. The KK modes are smooth near the brane and their
amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger
potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was
improved. Numerical analysis was adapted to the conventional notation on
Kaluza-Klein number. Some graphics were modified for considering other
notation. Results unchanged. References added. Corrected typos. 17 pages. 6
figures. To match version to appears in Physics Letters
Thermostatistics of overdamped motion of interacting particles
We show through a nonlinear Fokker-Planck formalism, and confirm by molecular
dynamics simulations, that the overdamped motion of interacting particles at
T=0, where T is the temperature of a thermal bath connected to the system, can
be directly associated with Tsallis thermostatistics. For sufficiently high
values of T, the distribution of particles becomes Gaussian, so that the
classical Boltzmann-Gibbs behavior is recovered. For intermediate temperatures
of the thermal bath, the system displays a mixed behavior that follows a novel
type of thermostatistics, where the entropy is given by a linear combination of
Tsallis and Boltzmann-Gibbs entropies.Comment: 4 pages, 2 figure
Relação entre população larval de Oryzophagus oryzae e profundidade da água de irrigação do arroz.
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