Effective field theory for lambda-sigma⁰ mixing in nuclear matter

We extend the effective field theory approach which successfully describes ordinary nuclei and nuclear matter to incorporate strangeness in nuclear structure. Central object is a chiral effective Lagrangian involving the baryon octet, the Goldstone boson octet, the vector meson octet and a light scalar singlet. According to the rules of effective field theory, we include all interaction terms (up to a given order of truncation) that are consistent with the underlying symmetries of QCD. We develop a mean-field approximation and study nuclear matter as a simple model for multi-strange systems. A D-type Yukawa coupling between baryons and vector mesons leads to lambda-sigma^0 flavor mixing in the nuclear medium. We study flavor oscillations in the nuclear matter ground state which are closely related to the phenomenon of neutrino oscillations.