169 research outputs found
New Model of Higher-Spin Particle
We elaborate on a new model of the higher-spin (HS) particle which makes
manifest the classical equivalence of the HS particle of the unfolded
formulation and the HS particle model with a bosonic counterpart of
supersymmetry. Both these models emerge as two different gauges of the new
master system. Physical states of the master model are massless HS multiplets
described by complex HS fields which carry an extra U(1) charge q. The latter
fully characterizes the given multiplet by fixing the minimal helicity as q/2.
We construct the twistorial formulation of the master model and discuss
symmetries of the new HS multiplets within its framework.Comment: 13 pages, talk given by E. Ivanov at the XII International Conference
on Symmetry Methods in Physics (SYMPHYS-XII), Yerevan, Armenia, July 03 - 08,
2006; to be published in the Proceeding
Random mode coupling assists Kerr beam self-cleaning in a graded-index multimode optical fiber
In this paper, we numerically investigate the process of beam self-cleaning in a graded-index multimode optical fiber, by using the coupled-mode model. We introduce various models of random linear coupling between spatial modes, including coupling between all modes, or only between degenerate ones, and investigate the effects of random mode coupling on the beam self-cleaning process. The results of numerical investigations are in complete agreement with our experimental data
Massive relativistic particle model with spin from free two-twistor dynamics and its quantization
We consider a relativistic particle model in an enlarged relativistic phase
space M^{18} = (X_\mu, P_\mu, \eta_\alpha, \oeta_\dalpha, \sigma_\alpha,
\osigma_\dalpha, e, \phi), which is derived from the free two-twistor dynamics.
The spin sector variables (\eta_\alpha, \oeta_\dalpha, \sigma_\alpha,\
osigma_\dalpha) satisfy two second class constraints and account for the
relativistic spin structure, and the pair (e,\phi) describes the electric
charge sector. After introducing the Liouville one-form on M^{18}, derived by a
non-linear transformation of the canonical Liouville one-form on the
two-twistor space, we analyze the dynamics described by the first and second
class constraints. We use a composite orthogonal basis in four-momentum space
to obtain the scalars defining the invariant spin projections. The
first-quantized theory provides a consistent set of wave equations, determining
the mass, spin, invariant spin projection and electric charge of the
relativistic particle. The wavefunction provides a generating functional for
free, massive higher spin fields.Comment: FTUV-05-0919, IFIC-05-46, IFT UWr 0110/05. Plain latex file, no
macros, 22 pages. A comment and references added. To appear in PRD1
Beam self-cleaning in multimode optical fibers and hydrodynamic 2D turbulence
We experimentally demonstrate the conservation of the average mode number in the process of Kerr beam self-cleaning in a graded-index multimode optical fiber, in analogy with wave condensation in hydrodynamic 2D turbulence
Nonlinear pulse combining and compression using twisted hexagonal multi-core fibers
We demonstrate numerically and analytically that the twisting of the 7-core hexagonal fiber leads to an increase in the efficiency of pulse combining and to a reduction of the distance along the fiber to the combining point
Taming the zoo of supersymmetric quantum mechanical models
We show that in many cases nontrivial and complicated supersymmetric quantum
mechanical (SQM) models can be obtained from the simple model describing free
dynamics in flat complex space by two operations: (i) Hamiltonian reduction and
(ii) similarity transformation of the complex supercharges. We conjecture that
it is true for any SQM model.Comment: final version published in JHE
Justification of an asymptotic expansion at infinity
A family of asymptotic solutions at infinity for the system of ordinary
differential equations is considered. Existence of exact solutions which have
these asymptotics is proved.Comment: 8 page
Sub-critical regime of femtosecond inscription
We apply well known nonlinear diffraction theory governing focusing of a powerful light beam of arbitrary shape in medium with Kerr nonlinearity to the analysis of femtosecond (fs) laser processing of dielectric in sub-critical (input power less than the critical power of selffocusing) regime. Simple analytical expressions are derived for the input beam power and spatial focusing parameter (numerical aperture) that are required for achieving an inscription threshold. Application of non-Gaussian laser beams for better controlled fs inscription at higher powers is also discussed. © 2007 Optical Society of America
An unusual case of cardiac dysfunction after left ventricular reconstruction
This report describes an unusual cause of low cardiac output after coronary artery bypass grafting and left ventricular remodeling. It details left ventricular remodeling techniques and discusses the most recent advances and outcomes. As well, significant attention is paid to the issues surrounding failure to separate from cardiopulmonary bypass
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