On the twist-2 contributions to polarized structure functions and new sum rules

TL;DR

This paper derives the twist-2 polarized structure functions for neutral and charged current deep inelastic scattering, using both operator product expansion and the covariant parton model. It shows that only two structure functions are independent per current combination, with WW and DIC relations and a new g3–g5 relation generating a set of sum rules. Light-quark mass corrections are computed in lowest order QCD, revealing mass-induced deviations in certain sum rules (notably BC) for EW processes, while maintaining Dicus and the equality of first moments for g3 and g4. The two methodological approaches agree, providing a coherent framework for EW polarized DIS analyses and future phenomenology. The findings have implications for interpreting polarized DIS data with weak currents and for constraining spin-dependent parton distributions in EW processes.

Abstract

The twist-2 contributions to the polarized structure functions in deep inelastic lepton--hadron scattering are calculated including the exchange of weak bosons and using both the operator product expansion and the covariant parton model. A new relation between two structure functions leading to a sequence of new sum rules is found. The light quark mass corrections to the structure functions are derived in lowest order QCD.