Few-Body Sigma and Lambda-Lambda Hypernuclear Systems

Abstract

The hypernucleus \(\overset{4}{\mathop{\Sigma }}\,\)He is a bound state with Jπ= 0+ and T ~ 1/2 (99%), of which binding energy and width are calculated to be B(Σ+) = 3.7 ~ 4.6 MeV and Г = 4.5 ~ 7.9 MeV. The nucleus-Σ potential derived from the realistic EN interaction is characterized by a strong Lane term and inner repulsion, which explain the appearance of the narrow-width bound state \(\overset{4}{\mathop{\Sigma }}\,\)He. The nucleus-Σ potential for heavy nuclei has a repulsive bump near the nuclear surface. A hybrid bound-state could be observed in 208Pb region, where Σ is trapped in the surface region by the peculiar-shaped nucleus-Σ potential with the aid of the Coulomb and the centrifugal potentials. Three types of the possible existence are discussed for Σ-hypernuclear systems.The double-Λ hypernucleus formation rate is calculated for a stopped Ξ- on 4He and on 6Li. In the case of 4He the released energy 28.33 MeV from the elementary process Ξ + p - → Λ + Λ is almost exhausted by breakup of the alpha particle of which binding energy is 28.30 MeV. The branching ratio of the double-Λ hypernucleus Λ\(\overset{4}{\mathop{\Lambda }}\,\)H formation from a Ξ-.4He atom is obtained to be 37 %, which is very high compared to the ratio of the Λ;\(\overset{6}{\mathop{\Lambda }}\,\)He formation from a Ξ-.6Li atom. The detection of about 2.3 MeV neutron is proposed to search for the lightest double-Λ hypernucleus Λ;\(\overset{4}{\mathop{\Lambda }}\,\)H.KeywordsAlpha ParticleHeavy NucleusNuclear SurfaceCentrifugal PotentialCentral RepulsionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.