Measurement of KN scattering below the KN mass threshold

Abstract

Abstract. We measured πE invariant mass spectra below and above the K¯N mass threshold in the K−d → NπE reaction in order to study the K¯N interaction and the Λ(1405) resonance. This reaction can be described by the two-step process: (i) K¯N1 → K¯N followed by (ii) K¯N2 → πΣ, where N1 and N2 are nucleons bound in the deuteron. We deduced the S -wave scattering amplitude of K¯N →K¯N in the framework of the K¯N πΣ coupled channel so as to reproduce the observed πΣ spectra in the I = 0 channel. We found a resonance pole at 1417.7-7.4+6.0 (fitting error)-1.0+1.1 (systematic error) - i[26.9-7.9+6.0 (fitting error)-2.0+1.7 (systematic error)]MeV/c2.