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The internal spin structure of the nucleon is described by structure functions in deep inelastic lepton-hadron scattering which are related to real, virtual and double virtual Compton scattering amplitudes by various sum rules connecting information at all energy scales. In this proceeding I concentrate on theoretical description of spin polarizabilities of double virtual Compton scattering. We use chiral perturbation theory to describe low energy QCD dynamics in a model independent way. I briefly review chiral perturbation theory activities in this field and show that the Jefferson Lab experimental data at low virtuality are in fair agreement with ChPT calculations with explicit delta-resonance degrees of freedom. Though, preliminary experimental data indicate a disagreement with existing ChPT predictions. There are also discrepancies between two different calculations of generalized polarizabilities which use different power counting for delta degrees of freedom which will be discussed.

Helmholtz-Institut fur Strahlen- und Kernphysik (Theorie) andBethe Center for Theoretical Physics, Universitat Bonn,Nusallee 14-16, D-53115 Bonn, GermanyE-mail:hkrebs@itkp.uni-bonn.deNuclear forces are considered based on chiral perturbation theory with and without explicit ∆iso-bar degrees of freedom. We discuss the subleading corrections to chiral three-nucleon forces inthe ∆-less formalism which contain no additional free parameters. In the formalism with explicit∆isobar we present complete next-to-next-to-leading orderanalysis of nuclear forces. The per-turbative expansion of nuclear forces in the ∆-full case is shown to have much better convergencecompared with the ∆-less theory where the∆resonance is integrated out and is encoded in certainlow-energy constants.6th International Workshop on Chiral Dynamics, CD09July 6-10, 2009Bern, Switzerland