806 research outputs found
General Approach to the Quantum Kicked Particle in a Magnetic Field: Quantum-Antiresonance Transition
The quantum kicked particle in a magnetic field is studied in a weak-chaos
regime under realistic conditions, i.e., for {\em general} values of the
conserved coordinate of the cyclotron orbit center. The system
exhibits spectral structures [``Hofstadter butterflies'' (HBs)] and quantum
diffusion depending sensitively on . Most significant changes take
place when approaches the value at which quantum antiresonance
(exactly periodic recurrences) can occur: the HB essentially ``doubles'' and
the quantum-diffusion coefficient is strongly reduced. An
explanation of these phenomena, including an approximate formula for in a class of wave packets, is given on the basis of an effective
Hamiltonian which is derived as a power expansion in a small parameter. The
global quantum diffusion of a two-dimensional wave packet for all
is briefly considered.Comment: Revised Version, publishe
On the Possible Enhancement of the Magnetic Field by Neutrino Reemission Processes in the Mantle of a Supernova
URCA neutrino reemission processes under the conditions in the mantle of a
supernova with a strong toroidal magnetic field are investigated. It is shown
that parity violation in these processes can be manifested macroscopically as a
torque that rapidly spins up the region of the mantle occupied by such a field.
Neutrino spin-up of the mantle can strongly affect the mechanism of further
generation of the toroidal field, specifically, it can enhance the field in a
small neighborhood of the rigid-body-rotating core of the supernova remnant.Comment: 8 pages, late
Aspects of phi-meson production in proton-proton collisions
We analyze near-threshold cross section data for the reaction pp->pp phi
published by the DISTO collaboration and recent, still preliminary results
presented by the ANKE Collaboration. We formulate a procedure to evaluate the
OZI ratio at low energies by taking into account corrections from the
kinematics and the final-state interaction. Combining the new data with the few
measurements available at higher energies we give a limit for the OZI rule
violation and estimate the possible contribution from a five-quark baryonic
resonance coupled to the phi-p system.Comment: 6 pages, 4 figure
Pulsar Kicks With Sterile Neutrinos and Landau Levels
We use a model with two sterile neutrinos obtained by fits to the MiniBoone
and LSND experiments. Using formulations with neutrinos created by URCA
Processes in a strong magnetic field, so the lowest Landau level has a sizable
probability, we find that with known paramenters the assymetric sterile
neutrino emissivity might account for large pulsar kicks.Comment: 3 pages, 1 figur
Compensation method of geodynamic trend in the systems of geoelectric control
Compensation method of geodynamic trend in the systems of geoelectric control To ensure the safety of important national economic objects in the conditions of technogenic, biogenic and anthropogenic interference, it is advisable to carry out automated electromagnetic control of geodynamic processes on the basis of multipolar sensing system
Spin-down of neutron stars by neutrino emission
We study the spin-down of a neutron star during its early stages due to the
neutrino emission. The mechanism we consider is the subsequent collisions of
the produced neutrinos with the outer shells of the star. We find that this
mechanism can indeed slow down the star rotation but only in the first tens of
seconds of the core formation, which is when the appropriate conditions of flux
and collision rate are met. We find that this mechanism can extract less than 1
% of the star angular momentum, a result which is much less than previously
estimated by other authors.Comment: 9 pages, 2 eps figures, RevTeX 4-1. The paper was significantly
modified. Now it addresses only the issues of a neutron star spin-down.
Version to be published in Phys. Rev.
Analysis of noise characteristics of multichannel systems of the formation of signals of georadars with synthesized aperture
The noise characteristics of multichannel systems of forming signals based on hybrid frequency synthesizers with automatic compensation of phase distortions of direct digital synthesizers, which are used in the composition of georadars with synthesized aperture, are investigate
On the extraction of the quark mass ratio (m_d - m_u)/m_s from Gamma(eta' -> pi^0 pi^+ pi^-)/Gamma(eta' -> eta pi^+ pi^-)
The claim that the light quark mass ratio (m_d - m_u)/m_s can be extracted
from the decay width ratio Gamma(eta' -> pi^0 pi^+ pi^-)/Gamma(eta' -> eta pi^+
pi^-) is critically investigated within a U(3) chiral unitary framework. The
influence of the recent VES data on the eta' -> eta pi^+ pi^- decay is also
discussed.Comment: 9 pages, 1 figure, 6 table
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