Sigma-Nucleus Potential inA=28

Abstract

We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.

Hypernuclear structure with the Nijmegen ESC08 potentials

“…potentials are much less attractive than the nucleonic ones, reflecting the weaker strength of the NY compared to the NN potentials. Within the ESC08 model, the well-depths U (k = 0) in normal nuclear matter of the , , and hyperons are, respectively, −39, +16, −8 MeV, and thus in reasonable agreement with current experimental estimates of these quantities [20,21]. The partial wave decompositions of these values are given in Table III which also lists explicitly the contributions of the different (isospin) channels according to Eqs.…”

“…This serves to connect the NN, NY, and YY channels and is utilized to make a simultaneous fit to the NN and NY data with a restricted set ( 20) of free coupling constants, etc., see [8] for details. In particular, the BBM coupling constants are calculated via SU(3), using, together with the meson mixing angles, the fitted constants in the NN ⊕ NY analysis as input.…”

Maximum mass of hyperon stars with the Nijmegen ESC08 model

“…[12]. Both changes are expected to stiffen the resulting EOS and could thus possibly allow larger maximum masses of hyperon stars than found before, for the following reasons: The ESC08b YN potential features in particular a repulsive − N interaction in agreement with recent experimental indications [19], and in contrast to the previously used YN potentials. Therefore a smaller − fraction is now expected in β-stable matter.…”

Equation of State for Nucleonic and Hyperonic Neutron Stars With Mass and Radius Constraints

“…The Λ binding energy of Λ-hypernuclei is well reproduced by an attractive Woods-Saxon potential of depth - (Millener et al 1988). The analyses of the (π − , K + ) reaction data on medium to heavy nuclei (Noumi et al 2002) performed in Harada & Hirabayashi (2006) and Kohno et al (2006) revealed a moderately repulsive Σ-nuclear potential in the nuclear interior of around 10-40 MeV, while the fits to Σ − atomic data (Friedman & Gal 2007) indicate a clear transition from an attractive Σ potential in the surface, to a repulsive one in the interior, although the size of the repulsion cannot be precisely determined. As for the strangeness −2 systems, the Nagara event (Takahashi et al 2001) and other experiments providing consistency checks established the size of the ΛΛ interaction to be mildly attractive, (Dover & Gal 1983), while the missing-mass spectra of the -+ K K , ( ) reaction on a 12 C target suggest a milder attraction of −20 MeV (Fukuda et al 1998) or ∼−14±2 MeV (Khaustov et al 2000).…”