Hoyle state and rotational features in Carbon-12 within a no-core shell model framework

TL;DR

This study uses an extended no-core shell-model approach with a schematic interaction to explore the structure and rotational features of Carbon-12, providing new insights into the Hoyle state and alpha-clustering phenomena.

Contribution

It introduces a symmetry-guided shell-model framework with a limited model space to analyze the Hoyle state and rotational bands in Carbon-12, offering novel perspectives on nuclear shapes and clustering.

Findings

Insights into the many-body dynamics of the Hoyle state.

Identification of rotational features linked to alpha-clustering.

Guidance for ab initio models on nuclear structure.

Abstract

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.