Abstract

The traditional description for high energy near-forward scattering in QCD has two components a soft Pomeron Regge pole for the tensor glueball, and a hard BFKL Pomeron in leading order at weak coupling. On the basis of gauge/string duality, we present a coherent treatment of the Pomeron. In large-N QCD-like theories, we connect the BFKL regime (which disagrees with flat-space string theory) with the classic Regge regime (which roughly agrees with it), describing both simultaneously using curvedspace string theory. The problem reduces to finding the spectrum of a single j-plane Schroedinger operator. For ultraviolet-conformal theories. the spectrum exhibits a set of Regge trajectories at positive t, and a leading j-plane cut for negative t, the cross-over point being model-dependent. For theories with logarithmically running couplings, one instead finds a discrete spectrum of poles at all t, where the Regge trajectories at positive t continuously become a set of slowly-varying and closely-spaced poles at negative t. Our results agree with expectations for the BFKL Pomeron at negative t, and with the expected glueball spectrum at positive t, but provide a framework in which they are unified. Effects beyond the single Pomeron exchange are briefly discussed.

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