Mechanics of Quark Exchange in High-Energy Hadron Reactions at Forward Angles

The 2-quark back-angle scattering mechanism is shown to reproduce main features of high-energy $hh$ flavor-exchange reactions. Prospects for reduction of the reaction matrix element to a form of convolution of hadron wave functions with the hard scattering kernel are discussed. Wave function models suitable for convolution with the kernel, which is singular at small $x$, and the emerging form-factor types, are discussed.