Self consistent propagation of hyperons and antikaons in nuclear matter based on relativistic chiral SU(3) dynamics
We evaluate the antikaon spectral density in isospin symmetric nuclear matter. The in-medium antikaon-nucleon scattering process and the antikaon propagation is treated in a self consistent and relativistic manner where a maximally scheme-independent formulation is derived by performing a partial density resummation in terms of the free-space antikaon-nucleon scattering amplitudes. The latter amplitudes are taken from a covariant and chiral coupled-channel SU(3) approach which includes s-, p- and d-waves systematically. Particular care is taken on the proper evaluation of the in-medium mixing of the partial waves. Our analysis establishes a rich structure of the antikaon spectral function with considerable strength at small energies. At nuclear saturation density we predict attractive mass shifts for the $Λ(1405)$, $Σ(1385)$ and $Λ(1520)$ of about 60 MeV, 60 MeV and 100 MeV respectively. The hyperon states are found to exhibit at the same time an increased decay width of about 120 MeV for the s-wave $Λ(1405)$, 70 MeV for the p-wave $Σ(1385)$ and 90 MeV for the d-wave $Λ(1520)$ resonance.