Abstract
The energy-level structure of the nucleus at a few MeV above the three- threshold is still unsatisfactorily known. For instance, most microscopic calculations predicted that there exist one state in this energy region besides the well-known Hoyle state, whereas some experimental and theoretical studies show the existence of two states. In this paper, I will take a -boson model for bound and continuum states in and study a transition process from the ground state to continuum states by the electric monopole operator. The strength distribution of the process will be calculated as a function of energy using the Faddeev three-body theory. The Hamiltonian for the system consists of two- and three- potentials, and some three- potentials with different range parameters will be examined. Results of the strength function show a double-peaked bump at the low-energy region, which can be considered as two states. The peak at higher energy may originate from a resonant state. However, it is unlikely that the peak at the lower energy is related to a resonant state, which suggests that it may be due to a so-called “ghost anomaly.” Distributions of decaying particles are also calculated.
- Received 23 November 2016
DOI:https://doi.org/10.1103/PhysRevC.94.061603
©2016 American Physical Society