Equivalent hyperon-nucleon interactions in low-momentum space

Equivalent interactions in a low-momentum space for the $\Lambda N$, $\Sigma N$ and $\Xi N$ interactions are calculated, using the SU$_6$ 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 $YN$ 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

Spin dependent momentum distributions of proton-deuteron clusters in 3He from electron scattering on polarized 3He: theoretical predictions

The process $\overrightarrow{^3{\rm He}}(e,e'\vec{p})d$ (or $\overrightarrow{^3{\rm He}}(e,e'\vec{d})p$) is studied theoretically in a Faddeev treatment with the aim to have access to the spin-dependent momentum distribution of ${\vec p} {\vec d}$ clusters in polarized $^3$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

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 $\Lambda$ of LMNN to gain good separability.Comment: 6 pages, 1 tabl

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