Model for the Pion-Pomeranchon Regge Cut in the Neutron-Proton Charge-Exchange Reaction

A model is developed in which the pion-Pomeranchon Regge cut in the $\mathrm{np}$ charge-exchange reaction is calculated from the Mandelstam diagram. We find that the Regge cut is self-conspiratory, and is determined by two parameters besides those associated with the pion pole and the Pomeranchon. The sharp forward peak is reproduced through the destructive interference between the pole and the cut. An excellent fit is obtained in the small-$t$ region, and the values of the parameters producing this fit agree with physical intuition.