7 Search Results
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Rotational bands beyond the Elliott model
Rotational bands are commonplace in the spectra of atomic nuclei. Inspired by early descriptions of these bands by quadrupole deformations of a liquid drop, Elliott constructed discrete nucleon representations of SU(3) from fermionic creation and annihilation operators. Ever since, Elliott's model has been foundational to descriptions of rotation in nuclei. Later work, however, suggested the symplectic extension Sp(3, R) provides a more unified picture. We decompose no-core shell-model nuclear wave functions into symmetry-defined subspaces for several beryllium isotopes, as well as 20Ne, using the quadratic Casimirs of both Elliott's SU(3) and Sp(3, R). The band structure, delineated by strong B(E2)more » -
Probing ab initio emergence of nuclear rotation
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Emergent Sp(3,$$\mathbb{R}$$) Dynamical Symmetry in the Nuclear Many-Body System from an Ab Initio Description
Ab initio nuclear theory provides not only a microscopic framework for quantitative description of the nuclear many-body system, but also a foundation for deeper understanding of emergent collective correlations. In this work, a symplectic Sp(3, $$\mathbb{R}$$) $$\supset$$ U(3) dynamical symmetry is identified in ab initio predictions, from a no-core configuration interaction approach, and found to provide a qualitative understanding of the spectrum of 7Be. Low-lying states form an Elliott SU(3) spectrum, while an Sp(3, $$\mathbb{R}$$) excitation gives rise to an excited rotational band with strong quadrupole connections to the ground state band. -
Probing ab initio emergence of nuclear rotation
Structural phenomena in nuclei, from shell structure and clustering to superfluidity and collective rotations and vibrations, reflect emergent degrees of freedom. Ab initio theory describes nuclei directly from a fully microscopic formulation. We can therefore look to ab initio theory as a means of exploring the emergence of effective degrees of freedom in nuclei. For the illustrative case of emergent rotational bands in the $Be$ isotopes, we establish an understanding of the underlying oscillator space and angular momentum (orbital and spin) structure. We consider no-core configuration interaction (NCCI) calculations for 7, 9, 11Be with the Daejeon16 internucleon interaction. Although shellmore »