Crossing Borders from Halo Nuclei to Cold Atoms: Universal Physics Embedding their Structure and Reactions
| Date/Time: | Thursday, 21 Mar 2019 from 4:10 pm to 5:00 pm |
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| Location: | A401 Zaffarano Hall |
| Contact: | |
| Phone: | 515-294-8894 |
| Channel: | College of Liberal Arts and Sciences |
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We will discuss the universal aspects exhibited by the properties of halo nuclei and atomic systems, in their structure and reactions, where few degrees of freedom play the dominant role. These few-body systems are described either by considering a cluster structure of a halo nuclei with weakly bound neutrons and a core or by atoms weakly interacting by Van der Waals forces. The relation of the bound and scattering properties of these systems to the so-called Efimov physics will be shown. It is expressed by universal aspects exhibited by the structure and reactions of weakly three-body exotic nuclei close to the neutron drip line like e.g. 22Carbon, and molecules, independent on the nuclear or atomic scales, when the range of the force is short, and large scattering lengths and bound system sizes. This is at the root of the close relation between the Thomas collapse and the Efimov effect.
The universal dependence on a few number of physical scales of the low-energy observables of these few-body systems are expressed in terms of correlations between them, which are limit cycles, obtained from cycles separated geometrically, when the interaction range is driven towards zero. The limit cycles are the result of the log-periodic behavior of the hamiltonian eigenstates, which appears when the range is driven towards zero with respect to the fixed physical size scales. Different correlations between s-wave observables are explored both in the continuum and discrete three-body spectrum for two neutron halo nuclei and also for molecular systems. For example, zeros of the s-wave phase shifts in the elastic scattering of a constituent and a bound two-body state, like e.g., neutron-deuteron, neutron-19Carbon, or in the atomic context 4He - (4He-23Na) are a common property, closely related to the log-periodicity of the continuum eigenstates. Therefore, it becomes a surprising possibility to simulate nuclear reactions of exotic s-wave halo nuclei by low-energy collisions of neutral atoms interacting with Van der Waals forces, when the Coulomb force is not playing a dominant role.
We will also shortly describe recent four-body formulations to describe, for example, the incomplete fusion of halo nuclei in collisions with heavy targets. Furthermore, we will discuss how these concepts permeate nuclear systems towards nuclear matter, where Pauli principle forbids the sensitivity to the short range physics beyond the alpha particle. Finally, we will present novel insights on how new limit cycles, different from the three-body Efimov one, appear when more particles are added to resonantly s-wave interacting bosonic systems and when strong mass asymmetries are possible, in close connection to recent experimental studies of heterogeneous atomic mass imbalanced systems.