Freedom Now: A New Look at the Impulse Approximation

Abstract

Recent work on a field-theoretic impulse approximation is described. The operator product expansion is organized according to powers of g(Q²), the effective coupling constant appropriate to momentum transfer Q², instead of asymptotic dimensional analysis. This allows the calculation of all quark and target mass dependence of lepton-hadron inclusive scattering, order by order in g(Q²). To O(g^°), there is scaling in a mass dependent variable, ξ. The correct incorporation of quark masses into the renormalization group analysis is presented; the consequences include the relation of constituent masses to current algebra and the magnitude and shapes of the parton distribution functions for gluons, antiquarks, and heavy quarks.