Compton scattering and fixed poles in parton field-theoretic models

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 T₁(ν,q²). In the language of Reggeization this is interpreted as a fixed pole at J=0 in T₁ and νT₂, with residue polynomial in the photon mass squared.