General formulas for invariant functions describing generalized γN→γN reactions within the method of effective Lagrangians
The crossed channels of generalized reaction \gamma N - \gamma N have been considered. The transformation coefficients from the independent helicity amplitudes to the invariant functions are calculated. The explicit expressions for invariant functions have been obtained with the subject to the contribution of Born diagrams in s-, u-, and t-channel and six resonances in s- and u-channel. It has been shown that the obtained invariant functions meet the requirements of crossing-symmetry.