This work is devoted to a Generator-Coordinate-Method investigation of the 16 B spectrum with an Extended Two-Cluster Model which includes many 15 B + n channels. We find that the narrow peak above the 15 B + n threshold seen in the experiments of Kalpachieva et al. and of Lecouey et al. can be assigned to a [Formula: see text] resonance. Several resonances are obtained near the 15 B + n threshold, in particular a [Formula: see text] state which could be a possible candidate for the 16 B ground state. Comparison with Shell Model calculations is performed.
Neutrinoless double-
β
decay matrix elements in large shell-model spaces with the generator-coordinate method