It is shown that high-energy inclusive and semi-inclusive cross sections can be calculated directly from field theories using functional integration techniques. The cross sections are related to certain classical solutions of the field equations. A single solution of the field equations satisfying all constraints was found when the method was applied to a ${\phi }^4$ quantum field theory. This solution gives an inclusive cross section with Feynman scaling and a reasonable transverse-momentum distribution in the semiclassical approximation.

• Received 10 October 1977

DOI:https://doi.org/10.1103/PhysRevD.17.1160