5,899 research outputs found
Capture of slow antiprotons by helium atoms
A consistent quantum mechanical calculation of partial cross-sections leading
to different final states of antiprotonic helium atom was performed. For the
four-body scattering wave function, corresponding to the initial state, as well
as for the antiprotonic helium wave function, appearing in the final tate,
adiabatic approximations was used. Calculations were carried out for a wide
range of antiprotonic helium states and incident energies of the antiproton.
Obtained energy dependances of some cross sections show a rich low energy
structure.Comment: 16 pages, 8 color pictures; the text, the bibliography, and the
pictures were slightly correcte
Exact calculations of a quasi-bound state in the system
Dynamically exact calculations of a quasi-bound state in the
three-body system are performed using Faddeev-type AGS
equations. As input two phenomenological and one chirally motivated
potentials are used, which describe the experimental information on the
system equally well and produce either a one- or two-pole structure
of the resonance. For the interaction
separable potentials are employed that are fitted to phase shifts obtained from
two theoretical models. The first one is a phenomenological
potential based on meson exchange, which is derived by SU(3) symmetry arguments
from the J\"ulich coupled-channels model. The other
interaction is a variant of the first one, which is adjusted to the s-wave
scattering length recently determined in lattice QCD simulations. The position
and width of the quasi-bound state is evaluated in two ways:
(i) by a direct pole search in the complex energy plane and (ii) using an
"inverse determinant" method, where one needs to calculate the determinant of
the AGS system of equations only for real energies. A quasi-bound state is
found with binding energy MeV and width
MeV, which could correspond to the
experimentally observed state.Comment: 18 pages, 2 figures, 2 table
On the Nature of Light Rays on the Moon
Lunar surface reflection of light rays from ground and spacecraft photographic dat
Measurement of the optical properties of lunar rocks in the transition zone, resulting from observations made by Lunokhod 2
Photometric measurements were carried out directly on the lunar surface with the aid of a calibration device, a plate with fields of different brightness, placed in the field of view of the panoramic telephotometers. The brightness of the fields of the calibration plate were measured in preliminary studies, relative to the brightness of a magnesia screen. This permitted determination of the reflectance features of the surficial lunar material relative to the standard most widely used in brightness studies of natural substances. The total brightness of sections a few centimeters across was recorded in direct proximity to the apparatus. The total area investigated in one panorama was about one square meter. Several areas in the mare and highland regions were studied. The albedos of various surface objects were obtained. A comparison of the brightness measurements with data from the RIFMA-M instrument discloses a correlation of the albedo change with change in chemical composition of the surface rock. Direct photometric studies of the lunar surface in the "mare-highland" transition zone assist in tracing the transition from one type of rock to another, and in obtaining information on the processes of material exchange between these two types of lunar landscape
Three-body calculation of the level shift in kaonic deuterium
The first calculation of kaonic deuterium level shift using Faddeev-type
equations was performed. The obtained results were compared with commonly used
approximate approaches.Comment: The version accepted in Phys. Lett.
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