Possible Existence of Light Σ Hypernuclei

Abstract

The possible existence of light 1: hypemuclei is discussed together with their general binding mechanism. The coupling between the isotriplet 1: particle (J:+,J: and 1:-) and the corresponding nuclear core isomultiplet and supermultiplet which comes from the strong isospin dependent and isospin-spin dependent terms of 1:-N interaction plays a crucial role to produce bound states of light 1: hypernuclei. It is found that 1) an almost pure isospin 1/2 bound (ground) state appears in !He mainly due to the cooperative contribution of the (tN· tx) and (tN· tx)(sN·sx) terms of 1:-N interaction, and 2) an isospin-breaking bound (ground) state appears in l:Li mainly due to the (tN· tx)(sN·sx) term of 1:-N interaction. We discuss in detail the different binding mechanism between !He and l:Li and propose a threshold rule for the formation of bound 1: hypemuclear states. From the viewpoint of the threshold rule, the possible existence of other typical light 1: hypernuclei, l:H, iBe and 11B, are investigated together with their binding mechanism on the same footing as !He and l:Li.