Connection of field matrix elements with the phases of two-channel $S$-wave scattering

An explicit expression is obtained that relates the physical $S$ matrix with the discontinuity across the kinematic cut of the matrix element $\langle 2|A(x)|0\rangle$ of a scalar field in the case of two ehanneis. The result obtained is a direct ge eralizatio of a result obtained by Troitskii and Shirokov [9] for the ease of a single channel.