4,379 research outputs found
Dual descriptions of massive spin-3 particles in via Noether gauge embedment
We present here a relationship among massive self-dual models for spin-3
particles in via the Noether Gauge Embedment procedure.
Starting with a first order model (in derivatives) we have obtained
a sequence of four self-dual models where . We
demonstrate that the procedure generate the correct action for the
auxiliary fields automatically. We obtain the whole action for the order
self-dual model including all the needed auxiliary fields to get rid of the
ghosts of the theory.Comment: 16 pages, 1 tabl
Master actions for massive spin-3 particles in D=2+1
We present here a relationship among massive self-dual models for spin-3
particles in via the master action procedure. Starting with a first
order model (in derivatives) we have constructed a master action
which interpolates among a sequence of four self-dual models where
. By analyzing the particle content of mixing terms, we give
additional arguments that explain why it is apparently impossible to jump from
the fourth order model to a higher order model. We have also analyzed
similarities and differences between the fourth order -term in the spin-2
case and the analogous fourth order term in the spin-3 context.Comment: 16 page
Exploring the Venus global super-rotation using a comprehensive General Circulation Model
The atmospheric circulation in Venus is well known to exhibit strong
super-rotation. However, the atmospheric mechanisms responsible for the
formation of this super-rotation are still not fully understood. In this work,
we developed a new Venus general circulation model to study the most likely
mechanisms driving the atmosphere to the current observed circulation. Our
model includes a new radiative transfer, convection and suitably adapted
boundary layer schemes and a dynamical core that takes into account the
dependence of the heat capacity at constant pressure with temperature.
The new Venus model is able to simulate a super-rotation phenomenon in the
cloud region quantitatively similar to the one observed. The mechanisms
maintaining the strong winds in the cloud region were found in the model
results to be a combination of zonal mean circulation, thermal tides and
transient waves. In this process, the semi-diurnal tide excited in the upper
clouds has a key contribution in transporting axial angular momentum mainly
from the upper atmosphere towards the cloud region. The magnitude of the
super-rotation in the cloud region is sensitive to various radiative parameters
such as the amount of solar radiative energy absorbed by the surface, which
controls the static stability near the surface. In this work, we also discuss
the main difficulties in representing the flow below the cloud base in Venus
atmospheric models.
Our new radiative scheme is more suitable for 3D Venus climate models than
those used in previous work due to its easy adaptability to different
atmospheric conditions. This flexibility of the model was crucial to explore
the uncertainties in the lower atmospheric conditions and may also be used in
the future to explore, for example, dynamical-radiative-microphysical
feedbacks.Comment: Accepted for publication in Planet. Space Sc
Massive "spin-2" theories in arbitrary dimensions
Here we show that in arbitrary dimensions there are two families of
second order Lagrangians describing massive "spin-2" particles via a
nonsymmetric rank-2 tensor. They differ from the usual Fierz-Pauli theory in
general. At zero mass one of the families is Weyl invariant. Such massless
theory has no particle content in and gives rise, via master action, to a
dual higher order (in derivatives) description of massive spin-2 particles in
where both the second and the fourth order terms are Weyl invariant,
contrary to the linearized New Massive Gravity. However, only the fourth order
term is invariant under arbitrary antisymmetric shifts. Consequently, the
antisymmetric part of the tensor propagates at large momentum as
instead of . So, the same kind of obstacle for the
renormalizability of the New Massive Gravity reappears in this nonsymmetric
higher order description of massive spin-2 particles.Comment: 11 pages, 0 figure
Massive spin-2 particles via embedment of the Fierz-Pauli equations of motion
Here we obtain alternative descriptions of massive spin-2 particles by an
embedding procedure of the Fierz-Pauli equations of motion. All models are free
of ghosts at quadratic level although most of them are of higher order in
derivatives. The models that we obtain can be nonlinearly completed in terms of
a dynamic and a fixed metric. They include some massive gravities
recently considered in the literature. In some cases there is an infrared (no
derivative) modification of the Fierz-Pauli mass term altogether with higher
order terms in derivatives. The analytic structure of the propagator of the
corresponding free theories is not affected by the extra terms in the action as
compared to the usual second order Fierz-Pauli theory.Comment: 13 page
Modulational instability of spatially broadband nonlinear optical pulses in four-state atomic systems
The modulational instability of broadband optical pulses in a four-state
atomic system is investigated. In particular, starting from a recently derived
generalized nonlinear Schr\"odinger equation, a wave-kinetic equation is
derived. A comparison between coherent and random phase wave states is made. It
is found that the spatial spectral broadening can contribute to the nonlinear
stability of ultra-short optical pulses. In practical terms, this could be
achieved by using random phase plate techniques.Comment: 9 pages, 3 figures, to appear in Phys. Rev.
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