The (π+, K+) Λ-hypernucleus production reaction in the response-function formalism

We present a detailed study of the excitation spectra of the Λ-hypernuclei obtained through the (π+, K+) reaction, and we compare our results for the cross sections with the most recent data from BNL and KEK experiments. The cross sections are obtained in the distorted-wave-impulse approximation (DWIA) with a proper optical potential for pions and kaons, obtained in the eikonal approximation. For the first time, a completely self-consistent treatment of the Λ-hypernuclei structure has been done, by means of the response-function method in the Hartree-Fock (HF) approximation with a Skyrme-type interaction. Moreover, the continuum is treated exactly with the Green-function method. Our results, from 12ΛC to 89ΛY, agree quite well with the experimental data. The shell model seems to give a very good description of these systems, where the Λ-particle occupies single-particle levels with no sign of collective effects and is uninhibited by the Pauli principle. Possible improvements of our model are suggested. ((orig.))