Few-Body Sigma and Lambda-Lambda Hypernuclear Systems

  • Yoshinori Akaishi
Conference paper
Part of the Few-Body Systems book series (FEWBODY, volume 5)


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.


Alpha Particle Heavy Nucleus Nuclear Surface Centrifugal Potential Central Repulsion 
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Copyright information

© Springer-Verlag Wien 1992

Authors and Affiliations

  • Yoshinori Akaishi
    • 1
  1. 1.Department of PhysicsHokkaido UniversitySapporo 060Japan

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