Finite volume corrections to forward Compton scattering off the nucleon

We calculate the spin-averaged amplitude for doubly virtual forward Compton scattering off nucleons in framework of manifestly Lorentz invariant baryon chiral perturbation theory at complete one-loop order $O(p^4)$. The calculations are carried out both infinite and a finite volume. obtained results allow detailed estimation finite-volume corrections to which can be extracted on lattice using background field technique.