Strong spin-orbit interaction in soft binary processes (the 3P0 model)

Binary processes 0+ 1/2 →0+ 1/2 (the amplitude M0+M1iσxnq/2q0) are studied using the Abramovskii-Kancheli-Kaidalov-LUND color-tube model. It is shown that the inclusion of vacuum 3P0 states in the wave function of the qq-bar pair produced when the color tube is broken is sufficient for obtaining a satisfactory description of the main features observed in processes at small q2: the large value (∼3) of the ratio M1/M0, the weak energy dependence of this ratio, and the identical q2 dependence of the two amplitudes. The q2 dependence of M/sub 0,1/ is determined by the parameter q0. The Thomas lxσ interaction gives a small contribution to M/sub 0,1/ which decreases logarithmically with energy. The inclusion of absorption leads to a small increase (∼1.3) in the ratio M1/M0