An extension to the Luscher's finite volume method above inelastic threashold (formalism)
An extension of the Lüscher’s finite volume method above inel astic thresholds is proposed. It is fulfilled by extendind the procedure recently proposed by HA L-QCD Collaboration for a single channel system. Focusing on the asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave functions (equal-time) near spatial infinity, a coupled cha nnel extension of effective Schrödinger equation is constructed by introducing an energy-independ ent interaction kernel. Because the NBS wave functions contain the information of T-matrix at lo ng distance, S-matrix can be obtained by solving the coupled channel effective Schrödinge r equation in the infinite volume.