Connecting structure functions on the lattice with phenomenology

Abstract

We examine the extraction of moments of parton distributions from lattice data, focusing in particular on the chiral extrapolation as a function of the quark mass. Inclusion of the correct chiral behavior of the spin-averaged isovector distribution resolves a long-standing discrepancy between the lattice moments and experiment. We extract the x-dependence of the valence u-d distribution from the lowest few lattice moments, and discuss the implications for the quark mass dependence of meson masses lying on the rho Regge trajectory. The role of chiral symmetry in spin-dependent distributions, and in particular the lattice axial vector charge, g_A, is also highlighted.Comment: 8 pages, 5 figures, plenary talk given by W. Melnitchouk at the 3rd Circum-Pan-Pacific Symposium on High Energy Spin Physics (Beijing, China, October 2001), to appear in Int. J. Mod. Phys.