14 research outputs found
Case study: calculation of a narrow resonance with the LIT method
The possibility to resolve narrow structures in reaction cross sections in
calculations with the Lorentz integral transform (LIT) method is studied. To
this end we consider a fictitious two-nucleon problem with a low-lying and
narrow resonance in the nucleon-nucleon partial wave and calculate the
corresponding ``deuteron photoabsorption cross section''. In the LIT method the
use of continuum wave functions is avoided and one works instead with a
localized function \tilde\Psi. In this case study it is investigated how far
into the asymptotic region \tilde\Psi has to be determined in order to obtain a
precise resolution of the artificially introduced E1 resonance. Comparing with
the results of a conventional calculation with explicit neutron-proton
continuum wave functions it is shown that the LIT approach leads to an
excellent reproduction of the cross section in the resonance region and of
further finer cross section details at higher energies. To this end, however,
for \tilde\Psi one has to take into account two-nucleon distances up to at
least 30 fm.Comment: 18 pages, 11 figure
Longitudinal response function of 4He with a realistic force
The longitudinal response function of 4He is calculated with the Argonne V18
potential. The comparison with experiment suggests the need of a three-body
force. When adding the Urbana IX three-body potential in the calculation of the
lower longitudinal multipoles, the total strength is suppressed in the
quasi-elastic peak, towards the trend of the experimental data.Comment: 3 pages, 3 figures, proceedings of the 20th European Conference on
Few-Body Problems in Physics (EFB20