Multiply Strange Nuclear Systems

• Published in: Annals of physics Vol. 235; no. 1; pp. 35 - 76
• Main Authors: Schaffner, J., Dover, C.B., Gal, A., Greiner, C., Millener, D.J., Stocker, H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.1994
• Subjects: 662340 > Hadron Interactions > (1992-); ACTINIDES; ALPHA DECAY RADIOISOTOPES; BARYON-BARYON INTERACTIONS; BARYONS; BASIC INTERACTIONS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; BINDING ENERGY; BOUND STATE; COMPOSITE MODELS; COUPLING CONSTANTS; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; ELEMENTARY PARTICLES; ELEMENTS; ENERGY; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; FERMIONS; HADRON-HADRON INTERACTIONS; HADRONS; HEAVY NUCLEI; HELIUM 4; HELIUM 5; HELIUM 7; HELIUM ISOTOPES; HYPERNUCLEI; HYPERON-HYPERON INTERACTIONS; HYPERONS; INTERACTIONS; INTERMEDIATE MASS NUCLEI; ISOTOPES; LAMBDA BARYONS; LAMBDA PARTICLES; LEAD 208; LEAD ISOTOPES; LIE GROUPS; LIGHT NUCLEI; MATHEMATICAL MODELS; MEAN-FIELD THEORY; MESON-BARYON INTERACTIONS; METALS; MINUTES LIVING RADIOISOTOPES; NICKEL 56; NICKEL ISOTOPES; NUCLEAR CORES; NUCLEAR FRAGMENTS; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEI; NUCLEONS; PARTICLE INTERACTIONS; PARTICLE MODELS; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; QUARK MODEL; RADIOISOTOPES; SECONDS LIVING RADIOISOTOPES; SIGMA BARYONS; SIGMA PARTICLES; STABILITY; STABLE ISOTOPES; STRANGE PARTICLES; STRONG INTERACTIONS; SU GROUPS; SU-3 GROUPS; SYMMETRY GROUPS; THORIUM; TIN 132; TIN ISOTOPES; XI BARYONS 663110 > General & Average Properties of Nuclei & Nuclear Energy Levels > (1992-); XI PARTICLES
• ISSN: 0003-4916; 1096-035X
• DOI: 10.1006/aphy.1994.1090

We investigate the stability of multiply strange baryonic systems, in the context of a mean field approach obtained from an underlying set of phenomenological meson-baryon interactions. The coupling parameters which determine the conventional σ + ω mean fields (Hartree potentials) seen by various baryon species (N, Λ, Ξ) in the many-body system are constrained by reproducing the trend of observed binding energies of single particle (N, Λ, Ξ) states, as well as the energy per particle and density of non-strange nuclear matter. We also consider additional scalar (σ*) and vector (φ) fields which couple strongly to strange baryons. The couplings of these fields are adjusted to produce strong hyperon-hyperon interactions, as suggested by the data on ΛΛ hypernuclei. Extrapolating this approach to systems of large strangeness S, we find a broad class of objects composed of neutrons, protons, Λ′s and Ξ′s, which are stable against strong decay. In these systems, the presence of filled Λ orbitals blocks the strong decay ΞN → ΛΛ, leading to a strangeness fraction fs = |S|/A ≍1, density ρ ≍ (2 - 3) ρ0, and charge fraction fq in the range − 0.1 <q/A < 0.1, comparable to that of hypothetical stable strange quark matter ("stranglets"), but with a low binding energy per particle EB/A ≍ −10 to −20 MeV. We compare with an approximate mass formula which qualitatively describes the results of the mean field calculations. Such weakly bound multi-strange objects can be stable for very large A, unlike ordinary nuclei, since the Coulomb repulsion generated by the protons is largely cancelled by the presence of a comparable number of Ξ′s, leading to a small net charge (positive or negative) of order A1/3. We comment on the weak decays of such subjects and the possibility of their production in relativistic heavy ion collisions.