Extending MCAS to hypernuclei and radiative-capture reactions

Using a Multi-Channel Algebraic Scattering (MCAS) approach we have analyzed the spectra of two hypernuclear systems, 9ΛBe and 13ΛC. We have studied the splitting of the two odd-parity excited levels (1/2− and 3/2−) at 11 MeV excitation in 13ΛC, originated by the weak Λ-nucleus spin-orbit force. We have also considered the splittings of the 3/2+ and 5/2+ levels in both 9ΛBe and 13ΛC, finding how they originate from couplings to the collective 2 + states of the core nuclei. In both hypernuclei, we suggest that there could be additional low-lying resonant states in the Λ-nucleus continua. From the MCAS approach one can extract also the full coupled-channel scattering wavefunction to be used in the calculation of various transition matrix elements. As a first application, we have considered the EM-transition matrix elements for the capture reaction α + 3He→7Be+γ