EXA2011

We have constructed effective separable meson-baryon potentials to match the equivalent chiral amplitudes with the parameters of the model fitted to the kaonic hydrogen and low energy $K^{-}p$ reactions data [1]. When the $\bar{K}N$ system is submerged in nuclear medium the $\bar{K}N$ scattering amplitude and the final state branching ratios exhibit a strong energy dependence when going to energies below the $\bar{K}N$ threshold [2]. The observed behavior is related to the dynamics of the well known $\Lambda(1405)$ resonance as well as to a combined effect of in-medium Pauli blocking and kaon selfenergy. A sharp increase of $\bar{K}N$ attraction below the $\bar{K}N$ threshold provides a link between shallow $\bar{K}$-nuclear potentials based on the chiral $\bar{K}N$ amplitude evaluated at threshold and the deep phenomenological optical potentials obtained in fits to kaonic atoms data. The energy and density dependence of the in-medium $R(K^{-}N \rightarrow \pi \Lambda)$ branching ratio has allowed us to explain the $A$-dependence of the $\Lambda$-hypernuclear production rates [3] measured by the FINUDA collaboration in the experiment with stopped kaons. Similarly, we demonstrate the impact of a subthreshold energy dependence of the in-medium $\bar{K}N$ amplitude on the characteristics of $\bar{K}$-nuclear states and on the construction of the $K^{-}$-nuclear optical potential used to describe the kaonic atoms data [2, 4]. [1] A.Cieply and J.Smejkal, Eur. Phys. J. A43 (2010) 191 [2] A.Cieply, E.Friedman, A.Gal, and D.Gazda, J.~Mares, ArXiv:1102.4515[nucl-th] [3] A.Cieply, E.Friedman, A.Gal and V.Krejcirik, Phys. Lett. B698 (2011) 226 [4] A.Cieply, E.Friedman, A.Gal, D.Gazda, and J.Mares, work in progress