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

Abstract

By using only a fraction of the model space extended beyond current no-core shell-model limits and a many-nucleon interaction with a single parameter, we gain additional insight within a symmetryguided 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 12 C, and in particular, the challenging Hoyle state and its first 2 + and 4 + excitations. For these states, we offer a novel perspective emerging out of no-core shell-model considerations, including a discussion of associated nuclear deformation and matter radii. This, in turn, provides guidance for ab initio shell models by informing key features of nuclear structure and the interaction.

Symmetry-guided large-scale shell-model theory

“…Once the γ parameter is fixed by the order of the three low-lying 0 + states in 12 C, excitation energies and other observables such as matter rms radii, electric quadrupole moments and E2 transition rates for various p-and sd-shell nuclei are found, with no parameter adjustment, to be in a remarkable agreement with the experiment [105,106,108] (see also Fig. 5 and Table 2).…”

Evidence for Triangular D3h Symmetry in C12Marín-Lámbarri1, Bijker2, Freer3 et al. 2014Phys. Rev. Lett.204142452View full textAdd to dashboardCite

“…The triatomic U(7) mixed-parity structure observed in 12 C resembles the diatomic U(4) mixed parity structure [7] The structure of 12 C has recently attracted much theoretical attention due to the availability of ab initio no-core shell model calculations [10], the no-core symplectic model [11] and Effective Field Theory (EFT) calculations on the lattice [12]. These calculations attempt to provide a microscopic description of cluster states that are well described in the traditional clustering model [13] and Antisymmetrized Molecular Dynamics (AMD) [14], as well as in the more modern Fermionic Molecular Dynamics (FMD) model [15] and more exotic cluster models [16].…”

Impact of off-diagonal cross-shell interaction on 14 C

“…The ab initio symmetry-adapted NCSM (SA-NCSM) results show that the multi-ω configuration mixing are important for the description of the collective modes in light nuclei, such as 6 Li, 6 He, and 8 Be [23,24]. The no-core symplectic shell model (NCSpM) are used to investigate the multi-ω configuration mixing in α-clustering substructures in the low-lying states of 12 C [25] and in ground state rotational bands of 20,22,24 Ne, 20 O, 20,22 Mg and 24 Si [26]. The effective Hamiltonian YSOX for psd region includes the effect of the off-diagonal cross-shell interaction based on the binding energies of B, C, N, and O isotopes from the stability line to the neutron drip line [27].…”