2,946 research outputs found
Equivalent hyperon-nucleon interactions in low-momentum space
Equivalent interactions in a low-momentum space for the , and interactions are calculated, using the SU quark model
potential as well as the Nijmegen OBEP model as the input bare interaction.
Because the two-body scattering data has not been accumulated sufficiently to
determine the hyperon-nucleon interactions unambiguously, the construction of
the potential even in low-energy regions has to rely on a theoretical model.
The equivalent interaction after removing high-momentum components is still
model dependent. Because this model dependence reflects the character of the
underlying potential model, it is instructive for better understanding of
baryon-baryon interactions in the strangeness sector to study the low-momentum
space interactions.Comment: 9 pages, 13 figures, accepted for publication in Phys. Rev.
On the usefulness of the spectral function concept
The usefulness of the spectral function S in the process 3He(e,e'N) has been
investigated in a kinematical regime constrained by the conditions that the
three-nucleon center-of-mass energy is less than 150 MeV and the magnitude of
the three-momentum transfer smaller than 600 MeV/c. Results based on a full
treatment of the final state interaction are compared to the spectral function
approximation. In the case of proton knockout in the direction of the photon
kinematical conditions have been identified where both response functions, RL
and RT, can be well approximated by S. These conditions occur for certain low
missing momenta and missing energies but not in all cases. So care is required.
In case of neutron knockout only RT is a candidate for an approximate treatment
by S. In the case of RL the concept of using S is not valid in the studied
kinematical regime. This does not exclude the possibility that beyond that
regime it might be useful. Possible applications using S for the extraction of
electromagnetic form factors of the nucleons are pointed out.Comment: 27 pages, 25 fugure
Proton polarizations in polarized 3He studied with the \vec{3He} (\vec{e},e' p)d and \vec{3He} (\vec{e},e' p)pn processes
We study within the Faddeev framework the \vec{3He} (\vec{e},e' p)d as well
as the \vec{3He} (\vec{e},e' p)pn and \vec{3He} (\vec{e},e' n)pp reactions in
order to extract information on the proton and neutron polarization in
polarized 3He. We achieve clear analytical insight for simplified dynamical
assumptions and define conditions for experimental access to important 3He
properties. In addition we point to the possibility to measure the
electromagnetic proton form factors in the process \vec{3He} (\vec{e},e' p)d
which would test the dynamical picture and put limits on medium corrections of
the form factors.Comment: 38 pages, 22 figure
Separability of a Low-Momentum Effective Nucleon-Nucleon Potential
A realistic nucleon-nucleon potential is transformed into a low-momentum
effective one (LMNN) using the Okubo theory. The separable potentials are
converted from the LMNN with a universal separable expansion method and a
simple Legendre expansion. Through the calculation of the triton binding
energies, the separability for the convergence of these ranks is evaluated. It
is found that there is a tendency for the lower momentum cutoff parameter
of LMNN to gain good separability.Comment: 6 pages, 1 tabl
Spin dependent momentum distributions of proton-deuteron clusters in 3He from electron scattering on polarized 3He: theoretical predictions
The process (or
) is studied theoretically in a
Faddeev treatment with the aim to have access to the spin-dependent momentum
distribution of clusters in polarized He. Final state
interactions and meson exchange currents turn out to have a strong influence in
the considered kinematical regime (below the pion threshold). This precludes
the direct access to the momentum distribution except for small deuteron
momenta. Nevertheless, the results for the longitudinal and transverse response
functions are interesting as they reflect our present day understanding of the
reaction mechanism and therefore data would be very useful.Comment: 16 pages, 9 figure
Theoretical predictions for extraction of GEn from semi-inclusive electron scattering on polarized 3He based on various nucleon-nucleon interactions
The process 3He(e,e'n) with polarized electrons and 3He in the initial state
is theoretically analyzed with the aim to search for sensitivity to the
electric form factor of the neutron, GEn. Faddeev calculations based on five
high precision nucleon-nucleon force models are employed and stability versus
exchange of the nucleon-nucleon forces is demonstrated.Comment: 7 pages, 3 Postscript figure
Search for Three-Nucleon Force Effects in Two-Body Photodisintegration of 3He(3H) and in the Time Reversed Proton-Deuteron Radiative Capture Process
Faddeev calculations have been performed for nucleon-deuteron
photodisintegration of 3He(3H) and proton-deuteron radiative capture. The bulk
of the results is based on the AV18 nucleon-nucleon force and the Urbana IX
three-nucleon force together with explicit exchange currents or applying the
Siegert approach. Three-nucleon force effects are predicted for both processes
and supported by most of the data.Comment: 21 pages, 8 figures, modified version with changed figures,
conclusions unchanged, to appear in Phys.Rev.
Selectivity of the Nucleon Induced Deuteron Breakup and Relativistic Effects
Theoretical predictions for the nucleon induced deuteron breakup process
based on solutions of the three-nucleon Faddeev equation including such
relativistic features as the relativistic kinematics and boost effects are
presented. Large changes of the breakup cross section in some complete
configurations are found at higher energies. The predicted relativistic
effects, which are mostly of dynamical origin, seem to be supported by existing
data.Comment: 4 pages, 4 figure
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