2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/231244We compute the Compton scattering off the nucleons in the framework of manifestly covariant baryon chiral perturbation theory (B$χ$PT). The results for observables differ substantially from the corresponding calculations in heavy-baryon chiral perturbation theory (HB$χ$PT), most appreciably in the forward kinematics. We verify that the covariant $p^3$ result fulfills the forward-Compton-scattering sum rules. We also explore the effect of the $Δ$(1232) resonance. We find that the substantial effect of the $Δ$-excitation on the nucleon polarizabilities can naturally be accommodated in the manifestly covariant calculation.7 pages, 4 figures, to appear in in the proceedings of the International Workshop on Effective Field Theories: from the Pion to the Upsilon. EFT09, Valencia, 1-6 Feb. 2009Nuclear Theorytext