Universal Properties of Weakly Bound Two-Neutron Halo Nuclei
We construct an effective field theory of a two-neutron halo nucleus in the limit where the two-neutron separation energy B and the neutron-neutron two-body virtual energy ε n are smaller than any other energy scale in the problem, but the scattering between the core and a single neutron is not fine-tuned, and the Efimov effect does not operate. The theory has one dimensionless coupling which formally runs to a Landau pole in the ultraviolet. We show that many properties of the system are universal in the double fine-tuning limit. The ratio of the mean-square matter radius and charge radius is found to be < r$$^{2}_{m}$$ > / < r$$^{2}_{c}$$ > = Af(εn/B), where A is the mass number of the core and f is a function of the ratio ε n / B which we find explicitly. In particular, when B >> εn, < r$$^{2}_{m}$$ > / < r$$^{2}_{c}$$ > = 2/3 A . Here, the shape of the E1 dipole strength function also depends only on the ratio εn/B and is derived in explicit analytic form. We estimate that for the 22C nucleus higher-order corrections to our theory are of the order of 20% or less if the two-neutron separation energy is less than 100 keV and the s-wave scattering length between a neutron and a 20C nucleus is less than 2.8 fm.
- Research Organization:
- Univ. of Chicago, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- FG02-01ER41195; SC0009924
- OSTI ID:
- 1903170
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 21 Vol. 128; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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