Analytical continuation in alpha is thus justified. We demonstrate that such sum rules are always finite, even in the presence of Regge behavior, when subtraction temns in the underlying parton-proton u-channel dispersion relation are taken into account. Sum rules for general Compton amplitudes are derived an d a discussion of mass renormalization for electromagnetic self-energy correction of hadrons is presented. We also demonstrate that a general consequence of composite theories of hadrons wrth field-theoretic constituents which incorporates the above properties is thc existence of a constant energy-independent and qi-independent term in q/sup 2/) (a Kronecker delta'' delta /sub JO/ term) and a J = O fixed pole in more » T/sub 2/( nu, q/sup 2/). We show that a covariantly regularized model based on the infinite- momentum-frame techniques of Drell, Levy, and Yan is equivalent to the manifestly covariant nonperturbative parton model of Landshoff, Polkinghorne, and Short. « lessīS>A general nonperturbative model for the entire Compton amplitude which incoporates Bjorken scaling, gauge invariance, and Regge behavior is presented.
Precise measurements of polarized electroproduction and Drell-Yan processes in the deep inelastic limit will soon provide the first information on the higher-twist parton distributions identifies these soft quark modes with low momentum contributions arising from self-energy-type interactions.
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