47 research outputs found
Consistent Treatment of Relativistic Effects in Electrodisintegration of the Deuteron
The influence of relativistic contributions to deuteron electrodisintegration
is systematically studied in various kinematic regions of energy and momentum
transfer. As theoretical framework the equation-of-motion and the unitarily
equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading
order relativistic -exchange contributions consistent with the Bonn OBEPQ
model are included. In addition, static heavy meson exchange currents including
boost terms, -currents, and -isobar contributions
are considered. Sizeable effects from the various relativistic two-body
contributions, mainly from -exchange, have been found in inclusive form
factors and exclusive structure functions for a variety of kinematic regions.Comment: 41 pages revtex including 15 postscript figure
Pion Absorption Cross Section for ^2H and ^3He in the Delta-Isobar Region: A Phenomenological Connection
The absorption of \pi^+ on ^3He in the -region is evaluated with
exact inclusion of the final state interaction among the three emerging
protons. The absorption is described by a vertex and a
transition t-matrix which are calculated from a phenomenological
model for NN and \pi d reactions. In a calculation where the initial pion
scattering effects are neglected, the predicted peaks of the pion absorption
cross sections for ^2H and ^3He lie too high in energy in relation to the data.
The effect of the final state three-nucleon interaction turns out to be too
small for changing the magnitude and shifting the peak position of the total
absorption cross section for ^3He. We demonstrate that the adjustment of the
peak position for the deuteron cross section by small modifications of the
-parameters, automatically leads to the correct peak position in ^3He.Comment: 12 pages, REVTeX, 10 PostScript figures, submitted to Phys. Rev.