Spin Structure Functions

Abstract

We review the theory and phenomenology of deep inelastic polarized lepton-nucleon scattering in the light of recent data with a deuteron target from the SMC at CERN and a Helium 3 target from the E142 experiment at SLAC. After including higher-order perturbative QCD corrections, mass corrections and updated estimates of higher-twist effects, we find good agreement with the basic Bjorken sum rule, and extract a consistent set of values for the quark contributions to the proton spin: $$\Delta \Sigma \equiv \Delta u+\Delta d+\Delta s=0.27\pm 0.11$$ $$\Delta u=0.82\pm 0.04,\Delta d=-0.44\pm 0.04,\Delta s=-0.11\pm 0.04$$ which are consistent with chiral soliton models and indications from lattice estimates. We also mention the prospects for future experiments on the spin structure of the nucleon.

Comments: 18 pages (LateX) + 6 postscript figures encoded through uufiles; CERN-TH-7022/93, TAUP-2094-93; Plenary talk at the PANIC '93 (corrected eq. (3) )