Forward virtual Compton scattering and the Lamb shift in chiral perturbation theory

Understand

We compute the spin-independent structure functions of the forward virtual-photon Compton tensor of the proton at one loop using heavy baryon chiral perturbation theory and dispersion relations.

• We study the relation between both approaches.
• We use these results to generalize some sum rules to virtual photon transfer momentum and relate them with sum rules in deep inelastic scattering.
• We then compute the leading chiral term of the polarizability correction to the Lamb shift of the hydrogen and muonic hydrogen.