108,546 research outputs found
Some remarks on the attractor behaviour in ELKO cosmology
Recent results on the dynamical stability of a system involving the
interaction of the ELKO spinor field with standard matter in the universe have
been reanalysed, and the conclusion is that such system does not exhibit
isolated stable points that could alleviate the cosmic coincidence problem.
When a constant parameter related to the potential of the ELKO field
is introduced in the system however, stable fixed points are found for some
specific types of interaction between the ELKO field and matter. Although the
parameter is related to an unknown potential, in order to satisfy the
stability conditions and also that the fixed points are real, the range of the
constant parameter can be constrained for the present time and the
coincidence problem can be alleviated for some specific interactions. Such
restriction on the ELKO potential opens possibility to apply the ELKO field as
a candidate to dark energy in the universe, and so explain the present phase of
acceleration of the universe through the decay of the ELKO field into matter.Comment: 17 pages, section III with minor changes and section IV rewritten
with a new analysi
On the duality of three-dimensional superfield theories
Within the superfield approach, we consider the duality between the
supersymmetric Maxwell-Chern-Simons and self-dual theories in three spacetime
dimensions. Using a gauge embedding method, we construct the dual theory to the
self-dual model interacting with a matter superfield, which turns out to be not
the Maxwell-Chern-Simons theory coupled to matter, but a more complicated
model, with a ``restricted'' gauge invariance. We stress the difficulties in
dualizing the self-dual field coupled to matter into a theory with complete
gauge invariance. After that, we show that the duality, achieved between these
two models at the tree level, also holds up to the lowest order quantum
corrections.Comment: 18 pages,2 figures, revtex4, v2: corrected reference
Experimental evidence of laser power oscillations induced by the relative Fresnel (Goos-Haenchen) phase
The amplification of the relative Fresnel (Goos-Haenchen) phase by an
appropriate number of total internal reflections and the choice of favorable
incidence angles allow to observe full oscillations in the power of a DPSS
laser transmitted through sequential BK7 blocks. The experimental results
confirm the theoretical predictions. The optical apparatus used in this letter
can be seen as a new type of two-phase ellipsometric system where the phase of
the complex refractive index is replaced by the relative Fresnel
(Goos-Haenchen) phase.Comment: 7 pages, 3 figures, 1 tabl
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