261 research outputs found
Meson retardation in deuteron electrodisintegration
The effect of meson retardation in -interaction and exchange currents on
deuteron electrodisintegration is studied in a coupled channel approach
including -, - and -channels. It is shown that the
influence of retardation depends on the energy regime: Whereas below
-threshold calculations with static and retarded operators yield almost
identical results, they differ significantly in the -region.
Especially, the longitudinal and the longitudinal-transverse interference
structure functions are strongly affected.Comment: 6 pages, 6 figure
Influence of final state interaction on incoherent pion photoproduction on the deuteron in the region of the Delta-resonance
The influence of final state - and pi N-rescattering in incoherent pion
photoproduction on the deuteron has been investigated. For the elementary
photoproduction operator an effective Lagrangian model is used which describes
well the elementary reaction. The interactions in the final two-body subsystems
are taken in separable form. While NN-rescattering shows quite a significant
effect, particularly strong for neutral pion production, pi N-rescattering is
almost negligible. Inclusion of such effects leads to an improved and quite
satisfactory agreement with experiment.Comment: 18 pages revtex4 including 16 postscript figure
Spin asymmetry and GDH sum rule for real and virtual photons for the deuteron
An explicit evaluation of the spin asymmetry of the deuteron and the
associated GDH sum rule is presented which includes disintegration, single and
double pion and eta production. For the GDH integral a large cancellation is
found between the disintegration channel and the meson production channels.
Furthermore, first results for the contribution of the disintegration channel
to the generalized GDH integral at constant four-momentum transfer reveal a
dominance of the isovector M1 transition to the S-state near threshold
resulting in a negative contribution with a minimum around
fm which is driven by the nucleon anomalous isovector magnetic moment.Comment: 9 pages, 7 figures, World Scientific style, invited talk at GDH 2004
Symposiu
Meson retardation in deuteron photodisintegration above pi-threshold
Photodisintegration of the deuteron above pi-threshold is studied in a
coupled channel approach including N Delta- and pi d-channels with pion
retardation in potentials and exchange currents. A much improved description of
total and differential cross sections in the energy region between pi-threshold
and 400-450 MeV is achieved.Comment: 12 pages revtex including 5 postscript figure
On the NN-final-state-interaction in the reaction
The influence of the mutual interaction between the two outgoing nucleons
(NN-FSI) in the reaction has been investigated.
Results for various kinematics are discussed. In general, the effect of
NN-FSI depends on kinematics and the chosen final state in the excitation
spectrum of .Comment: 12 pages Revtex including 4 postscript figure
The NN-final-state-interaction in two-nucleon-knockout reactions
The influence of the mutual interaction between the two outgoing nucleons
(NN-FSI) in electro- and photoinduced two-nucleon knockout from has
been investigated perturbatively. It turns out that the effect of NN-FSI
depends on the kinematics and on the type of reaction considered. In the
kinematics studied so far, the effect is larger in pp- than in pn-knockout and
in electron induced than in photoinduced reactions.Comment: 10 pages including 9 postscript figures, contribution to the 6th
workshop on "Electromagnetically Induced Two-Hadron Emission", Pavia,
September 24-27, 200
NN correlations and final-state interactions in (e,e'NN) reactions
After a brief overview of relevant studies on one-nucleon knockout showing
the importance of quantitatively understanding the origin of the quenched
spectroscopic factors extracted from data, attention is focussed on two-nucleon
emission as a suitable tool to investigate nucleon-nucleon correlations inside
complex nuclei. In particular, direct (e,epp) and (e,epn) reactions are
discussed, and the role of final-state interactions is studied. The influence
of the mutual interaction between the two outgoing nucleons is shown to depend
on the kinematics and on the type of the considered reaction.Comment: 13 pages, 4 figures. Proceedings of 2nd Int. Conf. on Nuclear and
Particle Physics with CEBAF at Jefferson Lab, Dubrovnik, 26-31 May 2003, to
be published on Fyzika
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