ABSTRACT
The Coulomb force makes itself felt no matter how far apart the colliding particles are from each other. The simplest way of finding the Coulomb scattering amplitude is to solve in parabolic coordinates; the method can be found in the standard texts. The cross section becomes arbitrarily large in the forward direction – so much so that the cross section is infinite. Classically speaking, the reason for this enormous amount of small angle scattering is that no matter how large the impact parameter of the incident particle, the long range of the Coulomb potential will cause a slight deflection, that is, a small angle scattering of the particle. For an attractive Coulomb interaction the Regge trajectory remains along the positive real axis all the way out to plus infinity. This is because this system has bound states for arbitrarily high angular momentum.
