Investigation of ${}^{23}\mathrm{N}$ in a three-body model

The neutron-drip-line nucleus ${}^{23}\mathrm{N}$ is investigated in a three-body model consisting of a ${}^{21}\mathrm{N}$ core and two valence neutrons. Using the Faddeev formalism with the realistic neutron-neutron potential and the neutron-core potential, we calculate the ground-state properties of ${}^{23}\mathrm{N}$ including its two-neutron separation energy, and obtain good agreement with the experiments. We also find an excited ${}^{23}\mathrm{N}$ state with a shallow two-neutron separation energy at about 0.18 MeV. By evaluating the root-mean-square matter radii, the average distances between the two valence neutrons, and the average distances from the core to the center of mass of the valence-neutron pair, we show that the excited state of ${}^{23}\mathrm{N}$ has a distinct halo structure. The large radius and very extended spatial distribution of the weakly bound excited state indicate the evidence of Efimov physics in the drip-line nucleus ${}^{23}\mathrm{N}$.

Figure 1

Three sets of Jacobi coordinates in the Faddeev formalism for the core+$n$+n three-body system.

Figure 2

Density distributions of neutrons in the subsystem ${}^{22}\mathrm{N}$. The solid curve is the density distribution of the core neutrons, and the dashed curve is the density distribution of the last neutron.

Figure 3

Contour diagram for the spatial correlation density distribution of the ground state of ${}^{23}\mathrm{N}$ with parameters of Set B.

Figure 4

Contour diagram for the spatial correlation density distribution of the ${\frac{1}{2}}^{-}$ excited state of ${}^{23}\mathrm{N}$ with parameters of Set B.