Time-delay in a multi-channel formalism

Understand

We reexamine the time-delay formalism of Wigner, Eisenbud and Smith, which was developed to analyze both elastic and inelastic resonances.

• An error in the paper of Smith has propagated through the literature.
• We correct this error and show how the results of Eisenbud and Smith are related.
• We also comment on some recent time-delay studies, based on Smith's erroneous interpretation of the Eisenbud result.