SLAC - PUB - 2085 February 1978 ( T / E ) IMPULSE APPROXIMATION AND SCALING VIOLATION IN QCD

The nature of the impulse approximation in local field theory is clarified by dividing the interaction Hamiltonian into two parts V and W, where V contains only those interactions causing large energy transfers. Partons are introduced as eigenstates of&%$?, + V, wheretio is the free Hamiltonian. Their time development is governed by the soft operator W, thus making it possible to use the impulse approximation in deep inelastic processes. Application is made to deep inelastic electron scattering and the Drell-Yan process. Making some reasonable assumptions on the parton matrix elements, the variation of parton density functions with Q2 is expressed in terms of a set of integrodifferential equations, which reduce to the known results when restricted to the longitudinal distributions. Explicit solutions of the scaling violation equations are obtained in some simple cases. * Work supported in part by the Dept. of Energy (Submitted to Phys. Rev.)