Three- and four-body cluster models of hypernuclei using the G-matrix Lambda N interaction - Be-9(Lambda), C-13(Lambda), He-6(Lambda Lambda) and Be-10(Lambda Lambda)

The structure calculations of He-5(Lambda), Be-9(Lambda), C-13(Lambda), Be-10(Lambda Lambda) and He-6(Lambda Lambda) are carried out with an accurate three- and four-body model method in which all rearrangement Jacobian coordinates and associated Gaussian basis functions are taken. The characteristic properties of the spin-independent parts of five kinds of YNG Lambda N interactions are focused on. We propose to improve the strengths of the odd-state parts in a systematic way. The improved YNG interaction explains the B-Lambda(He-5(Lambda)) and B-Lambda(Be-9(Lambda)) consistently without an additional three-body force. By employing the 3 alpha + Lambda four-body model together with the improved YNG interactions, the second 1/2(+) state of C-13(Lambda) is predicted as a bound state at approximately 1 MeV below the lowest threshold. The four-body model enables us to find that response to the addition of the Lambda particle to the core nucleus C-12 is very different for the ground and second 0(+) states. With the improved YNG interaction and the OBE-simulating Lambda Lambda interaction, the observed B-Lambda Lambda(Be-10(Lambda Lambda)) is reproduced in the framework of the 2 alpha + 2 Lambda four-body model. Anew theoretical prediction for B-Lambda Lambda(He-6(Lambda Lambda)) is made with the alpha + 2 Lambda three-body model.