207 research outputs found
Theory of nonlocal soliton interaction in nematic liquid crystals
We investigate interactions between spatial nonlocal bright solitons in nematic liquid crystals using an analytical (“effective particle”) approach as well as direct numerical simulations. The model predicts attraction of out-of-phase solitons and the existence of their stable bound state. This nontrivial property is solely due to the nonlocal nature of the nonlinear response of the liquid crystals. We further predict and verify numerically the critical outwards angle and degree of nonlocality which determine the transition between attraction and repulsion of out-of-phase solitons
See-Saw Energy Scale and the LSND Anomaly
The most general, renormalizable Lagrangian that includes massive neutrinos
contains ``right-handed neutrino'' Majorana masses of order M. While there are
prejudices in favor of M much larger than the weak scale, virtually nothing is
known about the magnitude of M. I argue that the LSND anomaly provides,
currently, the only experimental hint: M around 1 eV. If this is the case, the
LSND mixing angles are functions of the active neutrino masses and mixing and,
remarkably, adequate fits to all data can be naturally obtained. I also discuss
consequences of this ``eV-seesaw'' for supernova neutrino oscillations, tritium
beta-decay, neutrinoless double-beta decay, and cosmology.Comment: revtex, 4 pages, no figure
Multichannel oscillations and relations between LSND, KARMEN and MiniBooNE, with and without CP violation
We show by examples that multichannel mixing can affect both the parameters
extracted from neutrino oscillation experiments, and that more general
conclusions derived by fitting the experimental data under the assumption that
only two channels are involved in the mixing. Implications for MiniBooNE are
noted and an example based on maximal CP violation displays profound
implications for the two data sets (muon-neutrino and muon-antineutrino) of
that experiment.Comment: 5 pages 4 figure
Nonlocal stabilization of nonlinear beams in a self-focusing atomic vapor
We show that ballistic transport of optically excited atoms in an atomic
vapor provides a nonlocal nonlinearity which stabilizes the propagation of
vortex beams and higher order modes in the presence of a self-focusing
nonlinearity. Numerical experiments demonstrate stable propagation of lowest
and higher order vortices over a hundred diffraction lengths, before
dissipation leads to decay of these structures.Comment: 3 figure
Rotating soliton solutions in nonlocal nonlinear media
We discuss generic properties of rotating nonlinear wave solutions, the so
called azimuthons, in nonlocal media. Variational methods allow us to derive
approximative values for the rotating frequency, which is shown to depend
crucially on the nonlocal response function. Further on, we link families of
azimuthons to internal modes of classical non-rotating stationary solutions,
namely vortex and multipole solitons. This offers an exhaustive method to
identify azimuthons in a given nonlocal medium.Comment: 14 pages, 9 figures, 3 movies (external links
A new approach to the relativistic treatment of the fermion-boson system, based on the extension of the SL(2,C) group
A new technique for constructing the relativistic wave equation for the
two-body system composed of the spin-1/2 and spin-0 particles is proposed. The
method is based on the extension of the SL(2,C) group to the Sp(4,C) one. The
obtained equation includes the interaction potentials, having both the
Lorentz-vector and Lorentz-tensor structure, exactly describes the relativistic
kinematics and possesses the correct one-particle limits. The comparison with
results of other approaches to this problem is discussed.Comment: v3: revised version (to appear in Mod. Phys. Lett. A
Scattering of dipole-mode vector solitons: Theory and experiment
We study, both theoretically and experimentally, the scattering properties of
optical dipole-mode vector solitons - radially asymmetric composite
self-trapped optical beams. First, we analyze the soliton collisions in an
isotropic two-component model with a saturable nonlinearity and demonstrate
that in many cases the scattering dynamics of the dipole-mode solitons allows
us to classify them as ``molecules of light'' - extremely robust spatially
localized objects which survive a wide range of interactions and display many
properties of composite states with a rotational degree of freedom. Next, we
study the composite solitons in an anisotropic nonlinear model that describes
photorefractive nonlinearities, and also present a number of experimental
verifications of our analysis.Comment: 8 pages + 4 pages of figure
Nonlocal description of X waves in quadratic nonlinear materials
We study localized light bullets and X waves in quadratic media and show how the notion of nonlocality can provide an alternative simple physical picture of both types of multidimensional nonlinear waves. For X waves we show that a local cascading limit in terms of a nonlinear Schrödinger equation does not exist—one needs
to use the nonlocal description, because the nonlocal response function does not converge toward a function.
Also, we use the nonlocal theory to show that the coupling to the second harmonic is able to generate an X shape in the fundamental field despite having anomalous dispersion, in contrast to the predictions of the cascading limit
Modulational instability, solitons and beam propagation in spatially nonlocal nonlinear media
We present an overview of recent advances in the understanding of optical
beams in nonlinear media with a spatially nonlocal nonlinear response. We
discuss the impact of nonlocality on the modulational instability of plane
waves, the collapse of finite-size beams, and the formation and interaction of
spatial solitons.Comment: Review article, will be published in Journal of Optics B, special
issue on Optical Solitons, 6 figure
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