Abstract
We investigate the unbound nucleus in a three-body model. We use the hyperspherical formalism, which relies only on and interactions. As is unbound, even in its ground state, the long-range behavior of the wave functions is crucial. We adapt the -matrix technique to derive the wave functions and the associated phase shifts. We start from a potential which nicely reproduces the known properties. Using a weakly repulsive three-body potential, we find the ground state at 0.08 MeV, i.e., just above the threshold, in agreement with the latest experimental value. An analysis of the wave function suggests a dominant dineutron configuration. We extend the model to and . For , we find a relatively narrow resonance near MeV ( MeV), which is supported by recent experimental data. Broad structures are seen in the and phase shifts but cannot be associated with physical resonances.
- Received 22 September 2017
DOI:https://doi.org/10.1103/PhysRevC.96.054319
©2017 American Physical Society