The Coulomb Phase Revisited

Motivated by the forthcoming data from the E950 experiment at BNL for small angle polarized proton-carbon scattering we revisit the problem of Coulomb phase. The approximation usually used with the momentum transfer squared (q^2) small compared to the inverse elastic slope is not justified within the kinematics of the E950 experiment. We go beyond this approximation and derive a new rather simple expression which recovers the formula of Bethe at small q^2, but is valid at any momentum transfer.