Extraction of Hadron Interactions above Inelastic Threshold in Lattice QCD

We propose a new method to extract hadron interactions above inelastic threshold from the Nambu-Bethe-Salpter amplitude in lattice QCD. We consider the scattering such as $A+B\to C+D$, where $A,B,C,D$ are names of different 1-particle states. An extension to cases where particle productions occur during scatterings is also discussed.