2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198687The leading order contributions of processes involving anomalous pion-photon vertices to forward spin-dependent Compton scattering from nucleons are considered in heavy-baryon chiral perturbation theory. These all involve the exchange of three pions between one or two photons and the nucleon, and hence are two-loop processes. We find that the sum of these processes vanishes in the manner predicted by the low energy theorem of Low, Gell-Mann and Goldberger as the photon energy goes to zero. This provides the first consistency test of two-loop HBCPT.Minor typos corrected. 7 pages RevTeX, 1 eps figureHigh Energy Physics - PhenomenologyNuclear Theorytext