We extend a class of parton models to a fully gauge-invariant theory for the full Compton amplitude. The existence of local electromagnetic interactions is shown to always give rise to a constant real part in the high-energy behavior of the amplitude $T_1(\nu ,q^2)$. In the language of Reggeization this is interpreted as a fixed pole at $J=0\mathrm{}$ in $T_1$ and $\nu T_2$, with residue polynomial in the photon mass squared.

• Received 12 October 1971

DOI:https://doi.org/10.1103/PhysRevD.5.1384