Three-Body Binding and Resonant Mechanisms in Neutron-Rich Light Nuclei Far from Stability Line
Progress of Theoretical Physics Supplement
We study the typical Borromean systems of 4 He+n+n for 6 He and of 9 Li+n+n for 11 Li. In addition to these three body systems, we investigate the 8 He+n+n ground resonance state in 10 He. In understanding the binding mechanism of these loosely or unbound systems of the core+two valence neutrons, it is shown that the pairing correlation between valence neutrons becomes important. For the excited resonance states in 6 He and for the ground resonance state in 10 He, we extensively use the complex
... ely use the complex scaling method (CSM) to solve the three body resonance problems. The CSM is shown to be very useful not only for analysis of the observed 2 + state in 6 He and the ground state in 10 He but also for prediction of three new 2 + 2 , 1 + 1 and 0 + 2 resonance states in 6 He. These results present that the core+n+n model explains characteristic properties of 6 He. On the other hand, we discuss that a 9 Li+n+n model for 11 Li is not so simple as the 6 He case. To solve the binding energy problem, the 9 Li-n interaction is investigated in detail. Our much interest is concentrated on the the pairing correlation not only between valence neutrons but also between neutrons in the 9 Li-core. By taking into account pairing configurations in addition to the simple neutron (p 3/2 )-closed configuration, we show that the pairing blocking effect of core neutrons plays a very important role in understanding the low-lying single particle s-state in 10 Li and the strong state-depending 9 Li-n interaction. As a possibility of the experimental checking for the low-lying s-state in 10 Li, we discuss the observation of the so-called Thomas-Ehrman shift in the mirror nucleus 10 N, which has not been observed yet.