On the K− He4→Λπ− He3 resonant and non-resonant processes

The ongoing data analyses by the AMADEUS/KLOE-2 Collaboration on the 2004–2005 KLOE data revive studies of the K‾ nuclear absorption at low energies. The aim is to study K‾ interactions at subthreshold energies and to search for signals of K‾ meson nuclear states. In this paper the spectrum of the K− He4→Λπ− He3 reaction is discussed. One – calculable – mode of decay involves P-wave intermediate Σ(1385)Σ(1385) resonance. Another mode involves S-wave KN→ΛπKN→Λπ amplitude which may be extracted from the experimental results. Comparison of these two allows a check of subthreshold extrapolations of multichannel K‾N S-wave interaction models. Given the established significance of the P wave interaction in the K‾N system presented here, the obtained spectra will serve for the AMADEUS/KLOE-2 data analysis, in order to properly extract the subthreshold non-resonant transition amplitude.