Longitudinal structure functions

Abstract

We show that nonuniversality effects associated with heavy flavor excitations arise naturally when comparing longitudinal with transverse structure functions measured in muon and in neutrino induced reactions. Specifically, whereas in electromagnetic scattering of nuons charm excitation is dominated by the transverse cross section, the low Q 2 neutral and charged current neutrino scattering is predominantly given by the longitudinal cross section. The A dependence induced on R by the different Q 2 dependence of the transverse and longitudinal shadowing is also discussed.