Shell model study of Sigma and Lambda hypernuclear spectra from (K-, π±) reactions

Abstract

The pion inclusive spectra in the (K-, pi +or-) reactions leading to the formation of Lambda and Sigma hypernuclei have been investigated within the distorted wave impulse approximation. The wavefunctions of the hypernuclear states belonging to both bound as well as continuum parts of the spectrum have been obtained within a shell model framework. The hyperon-nucleus interaction is described by a Woods-Saxon form of the potential with parameters extracted from an earlier analysis of the (K-, pi ) data. The distortion waves in the entrance and outgoing channels are treated within the eikonal approximation. The results of the calculations are compared with the pion spectra derived from the kaon in-flight experiments on 12C and 16O nuclei. The author gets a good overall agreement with the experimental data for reactions leading to the formation of both Lambda And Sigma hypernuclei. This seems to demonstrate that the single particle shell model picture can be used to describe both Lambda and Sigma spectra rather well. Some implications of the spin orbit part of the Sigma -nucleus potential as inferred from this study on the structure of the Sigma hypernuclei are discussed.