The Λ(1405) Pole Structure from Lattice QCD: A Coupled-Channel Πς − KN Study

This report summarizes results of the first lattice QCD calculation of coupled-channel πΣ − K¯N scattering in the Λ(1405) region. This study was carried out using a single CLS ensemble with a heavier-than-physical pion mass mπ ≈ 200 MeV and a lighter-than-physical kaon mass mK ≈ 487 MeV. Once the finite-volume energy spectrum has been reliably extracted, the Lüscher method was employed to obtain scattering amplitudes. Through a variety of parametrizations of the two-channel K-matrix, the final results show a virtual bound state below the πΣ threshold and a resonance right below K¯N.