Old & new in strangeness nuclear physics

Abstract

Several persistent problems in strangeness nuclear physics are discussed in this opening talk at HYP2018, Norfolk VA, June 2018: (i) the 3 Λ H, and 3 Λ n if existing, lifetimes; (ii) charge symmetry breaking in Λ hypernuclei; (iii) the overbinding of 5 Λ He which might be related to the hyperon puzzle in neutron stars; and (iv) does Λ * (1405) survive in strange hadronic matter? Progress in Strangeness Nuclear Physics which 50 years ago consisted mostly of Hypernuclear Physics, with data collected exclusively in nuclear emulsions and bubble chambers, has been stepped up significantly with the advent of counter production experiments [1]. The left panel of Fig. 1 shows a 89 Y(π + , K + ) spectrum from KEK [2], exhibiting distinct Λ single-particle orbits in 89 Λ Y down to the ground-state (g.s.) s Λ orbit, a feature unparalleled in ordinary nuclei and hence termed "a textbook example of a shell model at work" [3].The right panel of Fig. 1 presents a compilation of most of the Λ hypernuclear binding energies (B Λ ) measured across the periodic table as a function of A −2/3 and as fitted by a simple 3-parameter Woods-Saxon (WS) potential. The Λ nuclear potential well depth D Λ in this simple-minded fit is 30 MeV, compared to 27.8±0.3 MeV from the 1988 first theoretical analysis [3] of the AGS (π + , K + ) data [4]. Although the robustness of extrapolating to A → ∞ is primarily owing to the (π + , K + ) production data in medium-weight and heavy nuclei, it is worth noting that D Λ was derived more than 50 years ago, to less accuracy of course, from π − decays of heavy spallation hypernuclei formed in silver and bromine emulsions [5,6]: 27±3 MeV (1964) and 27.2±1.3 MeV (1965), respectively.

Extended-soft-core baryon-baryon model ESC16. IV. S=−3 and S=−4 hyperon-hyperon interactions

“…The study of strangeness-rich systems in astrophysics is an important topic in the past 60 years with many contributions. We refer to the (general) review papers [24,25] for references. In particular, the -hyperon puzzle in neutron star matter [26] is reviewed in Ref.…”