Progress in the calculation of nucleon form factors and parton distribution functions

Abstract

Even though current lattice calculations are limited to unrealistically large quark masses, it is possible to implement the model independent constraints of chiral symmetry in extrapolations to the physical region. We discuss the role of the Δ-isobar in the extrapolation of the moments of spin dependent parton distribution functions. Unlike the unpolarised case, the Δ plays a crucial role for the isovector spin dependent distributions. We also present initial results for the extrapolation of isovector nucleon form factors, finding reasonably good agreement with experimental data.