TY - JOUR
T1 - Multiply strange nuclear systems
AU - Schaffner, Jürgen
AU - Dover, Carl B.
AU - Gal, Avraham
AU - Greiner, Carsten
AU - Millener, D. John
AU - Stöcker, Horst
PY - 1994/10
Y1 - 1994/10
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0001804578&partnerID=8YFLogxK
U2 - 10.1006/aphy.1994.1090
DO - 10.1006/aphy.1994.1090
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AN - SCOPUS:0001804578
SN - 0003-4916
VL - 235
SP - 35
EP - 76
JO - Annals of Physics
JF - Annals of Physics
IS - 1
ER -