# Münster 2017 – wissenschaftliches Programm

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# HK: Fachverband Physik der Hadronen und Kerne

## HK 37: Hauptvorträge II

### HK 37.3: Hauptvortrag

### Donnerstag, 30. März 2017, 09:50–10:30, F 1

**Few-neutron resonances and their impact on neutron-rich nuclei** — •Joel Lynn — Institut für Kernphysik, Technische Universität Darmstadt, Germany — ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH

The possibility of few-neutron structures has long intrigued the
theoretical and experimental nuclear physics community.
In addition to the inherent interest in the existence of such systems,
reproducing them theoretically will likely impose strong constraints on
the *T*=3/2 component of three-nucleon interactions, which in turn are
critical to the description of neutron-rich nuclei.
Thus, the existence of few-neutron resonances will have an important
impact on neutron-rich nuclei.
In this talk, I describe the historical situation up until now before
turning to our recent quantum Monte Carlo calculations of few-neutron
systems confined in external potentials based on local chiral
interactions at next-to-next-to-leading order in chiral effective field
theory.
These systems are calculated in different external Woods-Saxon
potentials and we assume that their extrapolation to zero
external-potential depth provides a quantitative estimate of three- and
four-neutron resonances.
The validity of this assumption is demonstrated by benchmarking with an
exact diagonalization in the two-body case.
We find that the extrapolated trineutron resonance is lower than the
tetraneutron resonance energy.
This suggests that a three-neutron resonance exists below a four-neutron
resonance in nature and is potentially measurable.
We confirm that the relative ordering of the resonances is not an
artifact of the external confinement, by demonstrating that the
odd-even staggering in the helium isotopic chain is reproduced within
this approach.

* This work is supported by the ERC Grant No. 307986 STRONGINT.