Gauge-Invariant Scaling Model of Current Interactions with Regge Behavior and Finite Fixed-Pole Sum Rules

A general nonperturbative model for the entire Compton amplitude which incorporates Bjorken scaling, gauge-invariance, and Regge behavior is pre- sented. We show that a covariantly regularized model based on the infinite momentum frame techniques of Drell, Levy, and Yan is equivalent to the mani- festly covariant nonperturbative parton model of Landshoff, Polkinghorne and Short. We also demonstrate that a general consequence of composite theories of hadrons with field-theoretic constituents which incorporates the above properties is the existence of a constant energy-independent and q2-independent term in T1@, q2) (a "Kronecker delta" 6 Jo term) and a J=O fixed pole in T2(~, q2). Sum rules for general Compton amplitudes are derived and a discussion of mass renormalization for electromagnetic self-energy corrections of hadrons is presented. We demonstrate that such sum rules are always finite, even in the presence of Regge behavior, when subtraction terms in the underlying parton proton u-channel dispersion relation are taken into account. Analytic continua- tion in 01 is thus justified.