Charge symmetry as an off-shell constraint on the nuclear force for finite range transformations

Abstract

An upper bound on the variation of the Coulomb subtracted pp scattering length in the 1S0 state is obtained for arbitrary unitary and Baker transformations of finite range. It is shown that this variation is always less than the experimental error in the nn scattering length, if the range of the transformation is less than about 1 fm, implying that Sauer's charge symmetry constraint is then automatically fulfilled. This also means that the charge symmetry principle is most relevant for the intermediate range of the nuclear force. We also discuss the zero-energy off-shell parameters which are actually constrained by charge symmetry and a knowledge of the outer part of the interaction. © 1976.