Emergence of clusters: Halos, Efimov states, and experimental signals

Abstract

We investigate emergence of halos and Efimov states in nuclei by use of a newly designed model which combines self-consistent mean-field and three-body descriptions. Recent interest in neutron heavy calcium isotopes makes ${}^{72}$Ca (${}^{70}$Ca+n+n) an ideal realistic candidate on the neutron dripline, and we use it as a representative example that illustrates our broadly applicable conclusions. By smooth variation of the interactions we simulate the crossover from well-bound systems to structures beyond the threshold of binding, and find that halo-configurations emerge from the mean-field structure for three-body binding energy less than $\sim 100$keV. Strong evidence is provided that Efimov states cannot exist in nuclei. The structure that bears the most resemblance to an Efimov state is a giant halo extending beyond the neutron-core scattering length. We show that the observable large-distance decay properties of the wave function can differ substantially from the bulk part at short distances, and that this evolution can be traced with our combination of few- and many-body formalisms. This connection is vital for interpretation of measurements such as those where an initial state is populated in a reaction or by a beta-decay.

arXiv comment5 pages, 5 figures, under review

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• Efimov Physics and Connections to Nuclear Physics
• Modeling ${}^{19}$B as a ${}^{17}$B-n-n three-body system in the unitary limit
• Three-body forces and Efimov physics in nuclei and atoms
• Universality of Efimov states in highly mass-imbalanced cold-atom mixtures with van der Waals and dipole interactions
• Possible halo structure of ${}^{62,72}$Ca by forbidden-state-free locally peaked Gaussians
• Combined few-body and mean-field model for nuclei
• Two-proton capture on the ${}^{68}$Se nucleus with a new self-consistent cluster model
• Two-cluster approach to the properties of one- and two-neutron-halo nuclei
• Deformation, halo, and bubble structure: A paradigm shift of exotic phenomena in light to medium mass nuclei
• Universal Efimov spectra and fermionic doublets in highly mass-imbalanced cold-atom mixtures with van der Waals and dipole interactions
• Uncertainty Quantification in Breakup Reactions
• ${}^{42}$Ca and ${}^{50}$Ca with the (Many- and Few-body) Unified Method