Dual model with Mandelstam analyticity for deep-inelastic electroproduction and annihilation

We present a dual model for virtual Compton amplitudes which satisfies the current-algebra constraints and exhibits Mandelstam analyticity. Mandelstam analyticity is crucial for making any contact to the deep-inelastic annihilation region, i.e., s, q², q^'2→+ ∞, and is accomplished by introducing nonlinear trajectories. The scaling properties of this model are mainly shaped by the current-algebra constraints. In terms of dual variables, the scaling limit occurs from the same configuration as the current-algebra fixed pole. We deal with two different choices of the trajectory. One gives back all the nice properties of the original Veneziano model. The other is inspired by the experimental finding of power behavior in large-angle scattering and its theoretical elucidation, the interchange model which requires asymptotically constant trajectories. The first choice leads to a light-cone representation and exhibits a new relation between the large-x behavior of the deep-inelastic annihilation structure function and the asymptotic behavior of the electromagnetic (2⁺){→}(1^-) transition form factor.