Calculation of Exclusive Cross Sections with the Lorentz Integral Transform Method

The longitudinal structure function of the d(e,e'p) exclusive cross section is calculated with the Lorentz integral transform method. In this approach final state interaction is fully taken into account, but without using a final state wave function. Cross sections are obtained via the inversion of the transform. It is shown that the inversion results are very stable. The comparison to a conventional calculation with an explicit np final state wave function shows that the obtained results are also very precise. Thus the method opens up the possibility to obtain exclusive cross sections for reactions with more than two particles, where it is generally very difficult to calculate the exact final state wave function.Comment: LaTeX, 15 pages, 8 ps figure

Photodisintegration of Three-Body Nuclei with Realistic 2N and 3N Forces

Total photonuclear absorption cross sections of $^3$H and $^3$He are studied using realistic NN and NNN forces. Final state interactions are fully included. Two NN potential models, the AV14 and the r-space Bonn-A potentials, are considered. For the NNN forces the Urbana-VIII and Tucson-Melbourne models are employed. We find the cross section to be sensitive to nuclear dynamics. Of particular interest in this work is the effect which NNN forces have on the cross section. The addition of NNN forces not only lowers the peak height but increases the cross section beyond 70 MeV by roughly 15%. Cross sections are computed using the Lorentz integral transform method.Comment: Results for Bonn potential with model Bonn rA instead of model rB. The Bonn rB results contained a small inexactness. After the correction it turned out that Bonn rA is more suited for our purpose because it leads to a binding energy of 8.15 MeV (about 0.25 MeV more than Bonn rB). In addition the results for the other realistic potentials models are improved at low energies (HH expansion was not completely convergent for the low-energy results). LaTeX, 8 pages, 4 ps figure

The 4^4He(e,e′p)3(e,e^\prime p)^3H Reaction with Full Final--State Interaction

An {\it ab initio} calculation of the $^4$He$(e,e^\prime p)^3$H longitudinal response is presented. The use of the integral transform method with a Lorentz kernel has allowed to take into account the full four--body final state interaction (FSI). The semirealistic nucleon-nucleon potential MTI--III and the Coulomb force are the only ingredients of the calculation. The reliability of the direct knock--out hypothesis is discussed both in parallel and in non parallel kinematics. In the former case it is found that lower missing momenta and higher momentum transfers are preferable to minimize effects beyond the plane wave impulse approximation (PWIA). Also for non parallel kinematics the role of antisymmetrization and final state interaction become very important with increasing missing momentum, raising doubts about the possibility of extracting momentum distributions and spectroscopic factors. The comparison with experimental results in parallel kinematics, where the Rosenbluth separation has been possible, is discussed.Comment: 17 pages, 5 figure

A small parameter approach for few-body problems

A procedure to solve few-body problems is developed which is based on an expansion over a small parameter. The parameter is the ratio of potential energy to kinetic energy for states having not small hyperspherical quantum numbers, K>K_0. Dynamic equations are reduced perturbatively to equations in the finite-dimension subspace with K\le K_0. Contributions from states with K>K_0 are taken into account in a closed form, i.e. without an expansion over basis functions. Estimates on efficiency of the approach are presented.Comment: 17 pages, 1 figur

Ab initio calculation of Li7 photodisintegration

The Li7 total photoabsorption cross section is calculated microscopically. As nucleon-nucleon interaction the semi-realistic central AV4' potential with S- and P-wave forces is taken. The interaction of the final 7-nucleon system is fully taken into account via the Lorentz Integral Transform (LIT) method. For the calculation of the LIT we use expansions in hyperspherical harmonics (HH) in conjunction with the HH effective interaction (EIHH) approach. The convergence of the LIT expansion is discussed in detail. The calculated cross section agrees quite well with the available experimental data, which cover an energy range from threshold up to 100 MeV.Comment: 11 pages with 3 figure