Possible existence of a bound state in Sigma 7Li.

The possible existence of a bound {sub {Sigma}}{sup 7}Li state is investigated within the frame of the microscopic {alpha}+ 2{ital N}''+{Sigma} cluster model by employing an effective {Sigma}-{ital N} interaction which reproduces the experimental binding energy and width of {sub {Sigma}}{sup 4}He. We found one bound state of {sub {Sigma}}{sup 7}Li with about a 1.2 MeV binding energy and about a 5.4 MeV width, which is composed mainly of ({sup 6}Li(g.s.){direct product}{Sigma}{sup 0}) and ({sup 6}He(g.s.){direct product}{Sigma}{sup +}) configurations. It is emphasized that the ({bold t}{sub {ital N}}{center dot}{bold t}{sub {Sigma}})({bold s}{sub {ital N}}{center dot}{bold s}{sub {Sigma}}) term of {Sigma}-{ital N} interaction plays an important role to produce the bound state. If the bound state is observed in a strangeness exchange reaction such as a {sup 7}Li({ital K}{sup {minus}},{pi}{sup {minus}}){sub {Sigma}}{sup 7}Li experiment, we can get direct information on the ({bold t}{sub {ital N}}{center dot}{bold t}{sub {Sigma}}) ({bold s}{sub {ital N}}{center dot}{bold s}{sub {Sigma}}) term of {Sigma}-{ital N} interaction.