In-medium Σ0–Λ mixing in QCD sum rules Original Research Article

The Σ0–Λ mixing angle in isospin-asymmetric nuclear medium is investigated by using QCD sum rules. From the general consideration of the in-medium baryonic correlations, in-medium baryon mixings are shown to have several Lorentz structures such as the scalar mixing angle θS and the vector mixing angle θV. This causes a difference between the particle mixing θ (=θS+θV) and the antiparticle mixing View the MathML source (=θS−θV). From the finite-energy sum rules for the Σ0–Λ mixing, we find that the in-medium part of the mixing angle has a relation θSMed∼−θVMed in the isospin-asymmetric medium. This implies that the medium affects mainly the antiparticle mixing. From the Borel sum rules, we obtain View the MathML source with θ0, ρn, ρp and ρ0 being the vacuum mixing angle, the neutron density, the proton density and the normal nuclear matter density, respectively.