Search results for "Quadrat"

Phenomenological applications of rational approximants

2016

We illustrate the powerfulness of Padé approximants (PAs) as a summation method and explore one of their extensions, the so-called quadratic approximant (QAs), to access both space- and (low-energy) time-like (TL) regions. As an introductory and pedagogical exercise, the function [Formula: see text] is approximated by both kind of approximants. Then, PAs are applied to predict pseudoscalar meson Dalitz decays and to extract [Formula: see text] from the semileptonic [Formula: see text] decays. Finally, the [Formula: see text] vector form factor in the TL region is explored using QAs.

Non-decoupling and lepton number violation in left-right models

1996

We argue that large non-decoupling effects of heavy neutrinos can appear naturally in manifestly left-right symmetric models due to the minimization conditions of the scalar potential and the structure of vev's imposed by phenomenology. We derive constraints on off-diagonal light-heavy and heavy-heavy neutrino mixings from the searches for lepton violating decays $\mu\rightarrow e\gamma,$ $\mu\rightarrow e e^-e^+$ and $\mu-e$ conversion in nuclei. The most stringent limits come from the latter process because its amplitude shows a quadratic non-decoupling dependence on the heavy neutrino mass. Due to the suppression of right-handed currents by large $W_R$ mass the present experiments are no…

Relations between polarization observables and complete sets for deuteron photodisintegration

1990

The polarization observables for deuteron photodisintegration are given as Hermitean forms of theT-matrix elementsti. By inversion we are able to express a given productti*tj in terms of polarization observables. This allows (i) to derive linear relations between observables for unpolarized, circularly and linearly polarized photons, (ii) to construct explicitly complete sets of polarization observables, and (iii) to derive quadratic relations between observables.

Evaluation of all-optical demultiplexing in millimeter-wave subcarrier-system for wireless communication

2006

In this paper, a scheme for multiplexing millimeter-wave carriers on a single optical carrier and using an all-optical millimeter-wave demultiplexer is presented. The optical demultiplexing of radio-over-fiber signals is based on dual sideband modulation with suppressed optical carrier combined with the filtering properties of dual over-written fiber Bragg gratings. The performance of the system is investigated using a single optical carrier and independent data modulated millimeter-wave signals at 20 and 40 GHz. The signals are transmitted over optical fiber, demultiplexed and wirelessly distributed to a mobile unit. It is found that performance of the demultiplexing using fiber Bragg grat…

Quantum transport of non-interacting Fermi gas in an optical lattice combined with harmonic trapping

2004

We consider a non-interacting Fermi gas in a combined harmonic and periodic potential. We calculate the energy spectrum and simulate the motion of the gas after sudden replacement of the trap center. For different parameter regimes, the system presents dipole oscillations, damped oscillations around the replaced center, and localization. The behaviour is explained by the change of the energy spectrum from linear to quadratic.

Mass of astrophysically relevantCl31and the breakdown of the isobaric multiplet mass equation

2016

The mass of $^{31}\mathrm{Cl}$ has been measured with the JYFLTRAP double-Penning-trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The determined mass-excess value, $\ensuremath{-}7034.7(34)$ keV, is 15 times more precise than in the Atomic Mass Evaluation 2012. The quadratic form of the isobaric multiplet mass equation for the $T=3/2$ quartet at $A=31$ fails $({\ensuremath{\chi}}_{n}^{2}=11.6)$ and a nonzero cubic term, $d=\ensuremath{-}3.5(11)$ keV, is obtained when the new mass value is adopted. $^{31}\mathrm{Cl}$ has been found to be less proton-bound, with a proton separation energy of ${S}_{p}=264.6(34)$ keV. Energies for the excited states in $^{31…

Multiparticle breathers for a chain with double-quadratic on-site potential

1999

We investigate the existence and properties of multiparticle breathers for a one-dimensional model with harmonic nearest neighbor interactions where a group of r particles $(r=1,2,3,\dots{})$ perform interwell oscillations between both wells of a double-quadratic on-site potiential. We find two types of such breathers. For the first type the breather frequency $\ensuremath{\Omega}$ is within the single-particle oscillator spectrum, and the ``residence'' time of each breather particle in the left and right well is about the same. For the second breather $\ensuremath{\Omega}$ is below that spectrum, and the ratio ${\ensuremath{\tau}}_{L}/{\ensuremath{\tau}}_{R}$ of the residence time in the l…

Stationary states of a two-state defect quadratically coupled to a few bosonic modes

1998

Abstract A fully quantistic microscopic two-phonon interaction model between an active centre and localized modes of an irradiated insulating material is introduced. Its exact diagonalization is accomplished with the help of a suitable unitary operator. Explicit expressions for the eigenvalues and eigenvectors are reported. The possible relevance of such a model in the context of the material science area is briefly pointed out.

A simple method for limiting the quadrature oscillator amplitude

1981

Robustness of quantum memories based on Majorana zero modes

2012

We analyze the rate at which quantum information encoded in zero-energy Majorana modes is lost in the presence of perturbations. We show that information can survive for times that scale exponentially with the size of the chain both in the presence of quenching and time-dependent quadratic dephasing perturbations, even when the latter have spectral components above the system's energy gap. The origin of the robust storage, namely the fact that a sudden quench affects in the same way both parity sectors of the original spectrum, is discussed, together with the memory performance at finite temperatures and in the presence of particle exchange with a bath.