One-boson-exchange potential model for the Λp interaction (II)

Abstract

This paper describes a one-boson-exchange potential model for the Λp interaction, which includes the ΣN channel explicitly. This model is an extension of a model we have previously discussed [1]. The extension consists of the addition of a unitary singlet pseudo-scalar meson ( χ 0) and an octet of scalar bosons. This extension enables us to fit the experimental low-energy Λp data with values of some meson-baryon couplings closer to generally preferred values than was possible with the previous model. In particular, the coupling of the unitary singlet vector meson (ω) to baryons is g ω 2/4 π = 4.5 in this model, whereas it was 24.9 in the earlier model. The present model contains the effects of nonets of pseudoscalar, vector and scalar bosons. The parameters of the model are boson and baryon masses, the couplings of the bosons to baryons and a spin-independent, channel-independent hard-core radius. SU(3) was used to relate the couplings. Four parameters of the model were adjusted to reproduce the most recent low-energy Λp data; all other parameters were fixed beforehand from other considerations. The adjusted parameters are the hard-core radius, the mass and coupling of a unitary singlet scalar boson, and the coupling of the neutral isospin-one member of the octet of scalar bosons to protons. The model provides a very good fit to the experimental Λp cross section data up to and above the ΣN threshold. The ( 3 S 1 − 3 D 1 ) partial cross sections are dominant just below the ΣN threshold, but one is not resonant there as it was the earlier model [1].