Four-body structure of ${}_{\Lambda }^7$Li and $\Lambda N$ spin-dependent interaction

Abstract

Two spin-doublet states of %$3/2^{+}$-$1/2^{+}$ and $7/2^{+}$-$5/2^{+}$ in ${}_{\Lambda }^7$Li are studied on the basis of the $\alpha +\Lambda +n+p$ four-body model. We employ the two-body interactions which reproduce the observed properties of any subsystems composed of $\alpha N$, $\alpha \Lambda$ and $\alpha NN$, and $\alpha \Lambda N$. Furthermore, the $\Lambda N$ interaction is adjusted so as to reproduce the $0^{+}$-$1^{+}$ splitting of in ${}_{\Lambda }^4$H. The calculated energy splittings of $3/2^{+}$-$1/2^{+}$ and $7/2^{+}$-$5/2^{+}$ states in ${}_{\Lambda }^7$Li are 0.69 MeV and 0.46 MeV, which are in good agreement with the resent observed data. The spin-dependent components of the $\Lambda N$ interaction are discussed.

6 pages, 2 figures, published to be in Phys. Rev. C