113 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
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
Polarization effects in the reaction and determination of the meson form factors in the time--like region
The electron positron annihilation reaction into four pion production has
been studied, through the channel . The
differential (and total) cross sections and various polarization observables
for this reaction have been calculated in terms of the electromagnetic form
factors of the corresponding current. The elements of the
spin--density matrix of the meson were also calculated. Numerical
estimations have been done, with the help of phenomenological form factors
obtained in the space--like region of the momentum transfer squared and
analytically extended to the time-like region.Comment: 19 pages, 2 figures, to appear in Phys Rev
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
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
Photodisintegration of aligned deuterons at astrophysical energies using linearly polarized photons
Following the model independent approach to deuteron photodisintegration with
linearly polarized rays, we show that the measurements of the tensor
analyzing powers on aligned deuterons along with the differential cross section
involve five different linear combinations of the isovector
amplitudes interfering with the isoscalar and amplitudes. This is
of current interest in view of the recent experimental finding
\cite{blackston1} that the three amplitudes are distinct and also the
reported experimental observation \cite{sawatzky} on the front-back (polar
angle) asymmetry in the differential cross section.Comment: 12 page
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