Hoyle state and rotational features in Carbon-12 within a no-core shell   model framework
  By using only a fraction of the model space extended beyond current no-core shell-model limits and a schematic effective many-nucleon interaction, we gain additional insight within a symmetry-guided shell-model framework, into the many-body dynamics that gives rise to the ground state rotational band together with phenomena tied to alpha-clustering substructures in the low-lying states in C-12, and in particular, the challenging Hoyle state and its first 2+ excitation. For these states, we offer a novel perspective emerging out of no-core shell-model considerations, including a discussion of associated nuclear shapes and matter radii. This, in turn, provides guidance for ab initio shell models by informing key features of nuclear structure and the interaction. 
Alison C. Dreyfuss, Kristina D. Launey, Tomas Dytrych, Jerry P.   Draayer, Chairul Bahri
nucl-th