Moments of polarized parton distribution functions

Abstract

We present novel results for the first moment of the spin-dependent structure function g 1 (x, Q 2) of the nucleon at “small” (Q 2 < 0.3 GeV2) photon virtuality in the framework of a relativistic formulation of baryon chiral perturbation theory. We perform a next-to-leading order calculation and obtain significant differences to previously found results based on the heavy-baryon approach for the proton and neutron.