359 research outputs found
Testing baryon number conservation in braneworld models with cold neutrons
In the context of multi-brane Universe models, matter swapping between two
braneworlds is allowed leading to a baryon number violation in our visible
world. An experimental framework is described to test such a phenomenology with
cold neutrons thanks to a neutron-shining-through-a-wall experiment.Comment: 4 pages, 1 figure. Proceedings of the ESS Science Symposium on
Neutron Particle Physics at Long Pulse Spallation Sources, NPPatLPS 2013
(25-27 March, 2013
Plausible "faster-than-light" displacements in a two-sheeted spacetime
In this paper, we explore the implications of a two-point discretization of
an extra-dimension in a five-dimensional quantum setup. We adopt a pragmatic
attitude by considering the dynamics of spin-half particles through the
simplest possible extension of the existing Dirac and Pauli equations. It is
shown that the benefit of this approach is to predict new physical phenomena
while maintaining the number of constitutive hypothesis at minimum. As the most
striking feature of the model, we demonstrate the possibility of fermionic
matter oscillations between the two four-dimensional sections and hyper-fast
displacements in case of asymmetric warping (without conflicting special
relativity). This result, similar to previous reported ones in brane-world
theories, is completely original as it is derived by using quantum mechanics
only without recourse to general relativity and bulk geodesics calculation. The
model allows causal contact between normally disconnected regions. If it proves
to be physically founded, its practical aspects could have deep implications
for the search of extra-dimensions.Comment: 17 pages, 1 figure. Final version. Accepted for publication in Phys.
Rev.
Quantum dynamics of particles in a discrete two-branes world model: Can matter particles exchange occur between branes?
In a recent paper, a model for describing the quantum dynamics of massive
particles in a non-commutative two-sheeted spacetime was proposed. This model
considers a universe made with two spacetime sheets embedded in a 5D bulk where
the fifth dimension is restricted to only two points. It was shown that this
construction has several important consequences for the quantum dynamics of
massive particles. Most notably, it was demonstrated that a coupling arises
between the two sheets allowing matter exchange in presence of intense magnetic
vector potentials. In this paper, we show that non-commutative geometry is not
absolutely necessary to obtain such a result since a more traditional approach
allows one to reach a similar conclusion. The fact that two different
approaches provide similar results suggests that standard matter exchange
between branes might finally occur contrary to conventional belief.Comment: 11 pages, no figures. Final version. Published in Acta Physica
Polonica
Non-reciprocal optical reflection from a bidimensional array of subwavelength holes in a metallic film
Using simulations and theoretical arguments we investigate the specular
reflection of a perforated gold film deposited on a glass substrate. A square
lattice of cylindrical holes is assumed to produce the periodic lateral
corrugation needed to hybridize the surface plasmons with radiative states. It
is shown that, contrasting transmission approaches, a knowledge of the
reflection on either side of the film provides separate information on the
gold-vacuum surface plasmons and on the gold-glass interface plasmons. Recent
experimental data on a specific implementation of this system are reexamined;
these show a good agreement between the measured reflections and the
simulations in both directions of incident wave probes. This confirms the
importance of taking into account the reflection asymmetry in the far-field
assessment of surface plasmons properties.Comment: 4 pages, 3 figures. Published versio
Bounded modes to the rescue of optical transmission
This paper presents a brief survey of the evolution of knowledge about
diffraction gratings. After recalling some basic facts, historically and
physically, we introduce the concept of Wood anomalies. Next, we present some
recent works in order to introduce the role of bounded modes in transmission
gratings. The consequences of these recent results are then introduced. This
paper is a secondary publication, published in Europhysics News (EPN 38, 3
(2007) 27-31). In the present version, some additional notes have been added
with related references.Comment: 6 pages, 6 figures. Secondary publication. Brief revie
C/CP symmetry violation of and transitions in a two-brane universe: a baryogenesis portal
For the past decade, there has been significant interest in the experimental
search for neutron-hidden neutron transitions as predicted by
various theoretical models, such as braneworld scenarios where the dark sector
resides on a hidden brane. In a recent study, it was demonstrated that a C/CP
asymmetry between and
transitions can explain baryogenesis. However, the origins of this asymmetry
and its required magnitude were only suggested. In this paper, we demonstrate
that both aspects naturally occur due to the presence of an extra scalar field
supported by the gauge group, which extends the conventional
electromagnetic gauge field in the two-brane universe.Comment: 6 pages, 2 figures, sequel of arXiv:2304.0724
Role of Wood anomalies in optical properties of thin metallic films with a bidimensional array of subwavelength holes
Recents works deal with the optical transmission on arrays of subwavelength
holes in a metallic layer deposited on a dielectric substrate. Making the
system as realistic as possible, we perform simulations to enlighten the
experimental data. This paper proposes an investigation of the optical
properties related to the transmission of such devices. Numerical simulations
give theoretical results in good agreement with experiment and we observe that
the transmission and reflection behaviour correspond to Fano's profile
correlated with resonant response of the eigen modes coupled with
nonhomogeneous diffraction orders. We thus conclude that the transmission
properties observed could conceivably be explained as resulting from resonant
Wood's anomalies.Comment: 7 pages, 10 figures, 2 table
Quantum vacuum photon-modes and superhydrophobicity
Nanostructures are commonly used for developing superhydrophobic surfaces.
However, available wetting theoretical models ignore the effect of vacuum
photon-modes alteration on van der Waals forces and thus on hydrophobicity.
Using first-principle calculations, we show that superhydrophibicity of
nanostructured surfaces is dramatically enhanced by vacuum photon-modes tuning.
As a case study, wetting contact angles of a water droplet above a polyethylene
nanostructured surface are obtained from the interaction potential energy
calculated as function of the droplet-surface separation distance. This new
approach could pave the way for the design of novel superhydrophobic coatings.Comment: 5 pages, 4 figures, final version published in Physical Review
Letter
Nanomorphology of the blue iridescent wings of a giant tropical wasp, "Megascolia procer javanensis" (Hymenoptera)
The wings of the giant wasp "Megascolia Procer Javanensis" are opaque and
iridescent. The origin of the blue-green iridescence is studied in detail,
using reflection spectroscopy, scanning electron microscopy and physical
modelling. It is shown that the structure responsible for the iridescence is a
single homogeneous transparent chitin layer covering the whole surface of each
wing. The opacity is essentially due to the presence of melanin in the
stratified medium which forms the mechanical core of the wing.Comment: 8 pages, 7 figures. Improved version. Accepted for publication in
Phys. Rev.
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