806 research outputs found

    General Approach to the Quantum Kicked Particle in a Magnetic Field: Quantum-Antiresonance Transition

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    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 xcx_{{\rm c}} of the cyclotron orbit center. The system exhibits spectral structures [``Hofstadter butterflies'' (HBs)] and quantum diffusion depending sensitively on xcx_{{\rm c}}. Most significant changes take place when xcx_{{\rm c}} approaches the value at which quantum antiresonance (exactly periodic recurrences) can occur: the HB essentially ``doubles'' and the quantum-diffusion coefficient D(xc)D(x_{{\rm c}}) is strongly reduced. An explanation of these phenomena, including an approximate formula for D(xc)D(x_{{\rm c}}) 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 xcx_{{\rm c}} 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

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    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

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    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

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    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

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    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

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    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

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    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^-)

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    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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