Lippmann-Schwinger equation multichannel

This multichannel matrix Green function determines a multichannel Lippmann-Schwinger equation... 

The multichannel Lippmann-Schwinger equation implies that w0 = u + GAvu. Substituting this into the second expression for K gives an alternative formula,... 

This expression is stationary for variations of u if and only if u is an exact solution of the multichannel Lippmann-Schwinger equation. The proof follows exactly as in the single-channel case, if the order of matrix products is maintained in the derivation. If the multichannel continuum solution is expanded as... 

E. 0. Alt, P. Grassberger, and W. Sandhas, Reduction of the three-particle collision problem to multichannel two-particle Lippmann-Schwinger equations, Nucl. Phys. B2 167 (1967). 

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