Strong Interactions at Large Transverse Momentum

The models of Blankenbecler, Brodsky, and Gunion for inclusive and exclusive reactions at large transverse momentum are examined in a covariant framework. The discussion of inclusive reactions is much less model-dependent than that of exclusive reactions, but it is argued that for both the rather specific assumptions of Blankenbecler, Brodsky, and Gunion should probably be relaxed. One can argue that, for inclusive reactions, there may be a connection between the power-law falloff in transverse momentum and the behavior of the structure functions for electroproduction and electron-positron annihilation at $\omega =1\mathrm{}$ and $\omega =0\mathrm{}$. The relation of large transverse-momentum inclusive amplitudes to Regge amplitudes at small transverse momentum is also discussed. For the exclusive process it is shown that a more detailed calculation suggests that the angular dependence is different from that calculated by Blankenbecler, Brodsky, and Gunion.