On the off-shell continuation of the physical transition operators

Summary  A generalized Gell-Mann-Goldberger formula for many-body symmetric transition operators is derived for arbitrary splittings of the channel external interactions. This exact formula is compared with previous results obtained for asymmetric transition operators. From our Gell-Mann-Goldberger formula we derive uncoupled integral equations with connected kernel for three-body symmetric transition operators. We compare these equations with similar equations obtained for transition operators having a different off-shell behaviour.