Chirally motivated $\bar{K}N$ amplitudes for in-medium applications

Abstract: A new fit of a chirally motivated coupled-channels model for meson-baryon interactions is presented including the recent SIDDHARTA data on the 1s level characteristics of kaonic hydrogen. The kaon-nucleon amplitudes generated by the model are fully consistent with our earlier studies. We argue that a sharp increase of the real part of the in-medium $K^{-}p$ amplitude at subthreshold energies provides a link between the shallow $\bar{K}$-nuclear optical potentials obtained microscopically from threshold $\bar{K}N$ interactions and the phenomenological deep ones deduced from kaonic atoms data. The impact on the $A$-dependence of the $\Lambda$-hypernuclear formation rates measured in reactions with stopped kaons is discussed too.