90 research outputs found
Temperature deformations of the mirror of a radio telescope antenna
The stress informed state of the mirror of an antenna, with a diameter of 3 m, for a radio interferometer used in space, and located in a temperature field is examined. The mirror represents a parabolic shell, consisting of 19 identical parts. The problem is based on representations of the thermoelasticity of thin shells
Distribution amplitudes and decay constants for mesons in light-front quark model
We present a calculation of the quark distribution amplitudes(DAs), the
Gegenbauer moments, and decay constants for and mesons using
the light-front quark model. While the quark DA for is somewhat broader
than the asymptotic one, that for meson is very close to the asymptotic
one. The quark DAs for and show asymmetric form due to the flavor
SU(3)-symmetry breaking effect. The decay constants for the transversely
polarized and mesons( and ) as well as the
longitudinally polarized ones( and ) are also obtained. Our
averaged values for , i.e. and
, are found to be consistent with other
model predictions. Especially, our results for the decay constants are in a
good agreement with the SU(6) symmetry relation,
.Comment: 12 pages, 6figure
Model-independent view on the low-mass proton-antiproton enhancement
We present a simple interpretation of the recently observed near-threshold
proton-antiproton enhancement. It is described by a set of low-energy
parameters deduced from the analysis of NantiN experiments at LEAR. We predict
a related effect in photoproduction reaction under study by CLAS collaboration.Comment: 10 pages, 2 figure
Electromagnetic Structure of the Meson in the Light-Front Quark Model
We investigate the elastic form factors of the rho meson in the light-front
quark model(LFQM). With the phenomenologically accessible meson vertices
including the one obtained by the Melosh transformation frequently used in the
LFQM, we find that only the helicity matrix element of the plus
current receives the zero-mode contribution. We quantify the zero-mode
contribution in the helicity amplitude using the angular condition of
spin-1 system. After taking care of the zero-mode issue, we obtain the
magnetic() and quadrupole() moments of the rho meson as and
, respectively, in the LFQM consistent with the Melosh transformation
and compare our results with other available theoretical predictions.Comment: 14pages, 5figure
Diagnostics of the Generation, Decay, and Transport of Artificial Plasma Perturbations by Means of Short Pulses of High-Power Radio Waves
© 2017 Springer Science+Business Media New YorkWe discuss the techniques of measuring and the possibilities of using short pulses of high-power radio waves for diagnostics of the properties of high- and low-frequency ionospheric plasma turbulence. The results of the experimental studies performed using the Sura heating facility are presented
Variations on the Deuteron
We consider few problems which are related to the deuteron and have simple
analytical solution. Relation is found between the deuteron electric quadrupole
moment and the -scattering amplitude. The degree of circular polarization
of photons is calculated for the radiative capture of longitudinally polarized
thermal neutrons. The anapole, electric dipole and magnetic quadrupole moments
of the deuteron are calculated.Comment: 14 pages, late
Airglow during ionospheric modifications by the sura facility radiation. Experimental results obtained in 2010
We present the results of studying the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red (λ = 630 nm) and green (λ = 557.7 nm) lines of atomic oxygen. Vertical sounding of the ionosphere (followed by modeling of the pump-wave propagation) and measurements of stimulated electromagnetic emission were used for additional diagnostics of ionospheric parameters and the processes occurring in the heated volume. © 2012 Springer Science+Business Media, Inc
Determining the Position and Properties of the Region of Artificial Ionospheric Irregularities Above the Sura Facility Responsible for Generation of Aspect Scattering Signals on a Short Path
© 2018, Springer Science+Business Media, LLC, part of Springer Nature. The data obtained in the experiments on aspect scattering on a short path of Kazan—Vasilsursk—Kazan performed at the Sura facility in 2010 at frequencies of 2–7 MHz are compared with the results of ray-tracing calculations of the sounding and scattered signals. Positions and sizes of the region above Sura responsible for generation of the aspect scattering signals are determined. Characteristic scales of artificial decameter scattering irregularities and their dynamic properties as functions of the generation altitude and the time of the day are found
The Lambda_b lifetime in the light front quark model
The enhancement of the Lambda_b decay width relative to B decay one due to
the difference of Fermi motion effects in Lambda_b and B is calculated in the
light--front quark model with the simplifying assumption that Lambda_b consists
of the heavy quark and light scalar diquark. In order to explain the large
deviation from unity in the experimental result for tau(Lambda_b)/tau(B), it is
necessary that diquark be light and the ratio of the squares of the Lambda_b
and B wave functions at the origin be \le 1.Comment: final journal version to appear in JETP Letter
Isoscalar short-range current in the deuteron induced by an intermediate dibaryon
A new model for short-range isoscalar currents in the deuteron and in the NN
system is developed; it is based on the generation of an intermediate dibaryon
which is the basic ingredient for the medium- and short-range NN interaction
which was proposed recently by the present authors.This new current model can
very well describe the experimental data for the three basic deuteron
observables of isoscalar magnetic type, viz. the magnetic moment, the circular
polarization of the photon in the process at thermal neutron
energies and the structure function B up to Q=60 fm.Comment: LaTex, 22 pages with 8 figure
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