Strangeness in nuclear physics

Abstract

We have shown that production, structure, and decays of Λ hypernuclei are intensively studied both theoretically and experimentally. From analysis of the excitation spectra and binding energies of hypernuclei we obtain additional information about the hyperon-nucleon interaction, especially about the spin-dependent part. This information is not accessible by today viable experiments on the Λ-nucleon scattering. The electroproduction of hypernuclei provides a possibility of studying highly-excited hypernuclear states which is difficult within the conventional γ-ray spectroscopy. The electroproduction of hypernuclei is also an important tool for testing models of the elementary hyperon production. The information about the elementary process allows us to learn about the baryon and meson resonances. We have verified that predictions of the DWIA shell-model calculations agree well with the spectra of 12ΛB and 16ΛN for the Λ in s-state. In the pΛ region more elaborate calculations, e.g. taking into account core-nucleus 1hω states, are needed to fully understand the new data. The Sacaly-Lyon model for the elementary process gives reasonable cross sections for the hypernucleus production which suggests that this model describes correctly the elementary process at forward angles.