Four-body structure of $^7_Λ$Li and $ΛN$ spin-dependent interaction

Abstract

Two spin-doublet states of %$3/2^+$-$1/2^+$ and $7/2^+$-$5/2^+$ in $^7_Λ$Li are studied on the basis of the $α+Λ+n+p$ four-body model. We employ the two-body interactions which reproduce the observed properties of any subsystems composed of $αN$, $αΛ$ and $αNN$, and $αΛN$. Furthermore, the $ΛN$ interaction is adjusted so as to reproduce the $0^+$-$1^+$ splitting of in $^4_Λ$H. The calculated energy splittings of $3/2^+$-$1/2^+$ and $7/2^+$-$5/2^+$ states in $^7_Λ$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 $ΛN$ interaction are discussed.