Effective kaon masses in dense nuclear and neutron matter

The effective mass and decay width of kaonic modes in baryonic matter are studied within a coupled-channel approach based on the Chiral SU(3) Effective Lagrangian which describes all available low energy data of the coupled KN, π∑, πΛ system. Including Pauli blocking and Fermi motion in the kaon dispersion relation, we find a strong non-linear density dependence of the K− effective mass and decay width in symmetric nuclear matter at densities around 0.1 times normal nuclear matter density ϱ0 due to the in-medium dynamics of the Λ(1405) resonance. At higher densities the K− effective mass decreases slowly but stays above 0.5 mK at least up to densities below 3 ϱ0. In neutron matter the K− effective mass decreases almost linearly with increasing density but remains relatively large (mK∗ > 0.65 mK) for ϱn ≲ 3 ϱ0. The K+ effective mass turns out to increase very slowly with rising density.