Variation of theRMatrix

The $R$ matrix of Wigner and Eisenbud is a function of a set of parameters (channel radii, boundary numbers, etc.) as well as of the energy of the incoming particle. Invariant imbedding techniques have been applied, which give the variation of the $R$ matrix with respect to changes of the parameters entering into the theory. A generalization of various formulas, derived originally by Wigner and Teichmann and Wigner, to the multichannel case has been obtained. Our general results apply also to deformations of the nucleus other than spherical. An application of the invariant imbedding technique is also shown concerning Robson's theory of the isobaric spin analogs.