In-medium kaon absorption in pion-induced reactions

In 2014 the HADES collaboration successfully performed two experimental campaigns with secondary pion beams. Hereby, one main focus was the investigation of the production as well as the properties of K⁰_S, K⁺, Φ and K^- in cold nuclear matter generated in pion-nucleon reactions (π^- + A, A = C, W) at p_π^- = 1.7 GeV/c. As already verified by the FOPI collaboration, the K⁰ production in pion-induced reactions mainly takes place at the surface of the nuclei (σ ∝ A^b, b = 2/3). While K^- can be absorbed in nuclear matter through strangeness exchange processes (K^-N → Yπ), no conventional absorption mechanism exists for K⁰ and K⁺. The question can be raised now how the K^- yield behaves? If an increase of the absorption with A would be dominant, a b < 2/3 should be observed. Although, a drop of the effective mass and thus a decrease of the kinematical threshold would lead to b > 2/3. In this talk we are showing the recent study of the K^- absorption achieved on the basis of the comparison of K^-/K⁺ ratios in both nuclear environments.