34,250 research outputs found
Latest measurements of beauty quark production at HERA
The latest results of beauty quark production measurements at HERA are
presented. New measurements have been obtained both in the photoproduction and
the deep inelastic scattering regimes. The results were compared with the NLO
QCD calculations.Comment: 3 pages, 2 figures. Talk presented at the 31st International
Conference on High Energy Physics (ICHEP02), Amsterdam, The Netherlands, July
24-31, 200
An Asymptotic Comparison of Two Time-homogeneous PAM Models
Both Wick-Ito-Skorokhod and Stratonovich interpretations of the parabolic
Anderson model (PAM) lead to solutions that are real analytic as functions of
the noise intensity e, and, in the limit e->0, the difference between the two
solutions is of order e^2 and is non-random.Comment: 12 page
Spectral analysis of electron transfer kinetics II
Electron transfer processes in Debye solvents are studied using a spectral
analysis method recently proposed. Spectral structure of a nonadiabatic
two-state diffusion equation is investigated to reveal various kinetic regimes
characterized by a broad range of physical parameters; electronic coupling,
energy bias, reorganization energy, and solvent relaxation rate. Within this
unified framework, several kinetic behaviors of the electron transfer kinetics,
including adiabatic Rabi oscillation, crossover from the nonadiabatic to
adiabatic limits, transition from the incoherent to coherent kinetic limits,
and dynamic bath effect, are demonstrated and compared with results from
previous theoretical models. Dynamics of the electron transfer system is also
calculated with the spectral analysis method. It is pointed out that in the
large reorganization energy case the nonadiabatic diffusion equation exhibits a
non-physical behavior, yielding a negative eigenvalue.Comment: submitted for a publication in Journal of Chemical Physic
A one-dimensional tunable magnetic metamaterial
We present experimental data on a one-dimensional superconducting
metamaterial that is tunable over a broad frequency band. The basic building
block of this magnetic thin-film medium is a single-junction (rf-)
superconducting quantum interference device (SQUID). Due to the nonlinear
inductance of such an element, its resonance frequency is tunable in situ by
applying a dc magnetic field. We demonstrate that this results in tunable
effective parameters of our metamaterial consisting of 54 SQUIDs. In order to
obtain the effective magnetic permeability from the measured data, we employ a
technique that uses only the complex transmission coefficient S21
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