Consequences of t-channel unitarity for gamma(*)p and gamma(*) gamma(*) amplitudes

Abstract

We show that t-channel unitarity constraints make it possible to obtain the photon-photon cross sections from the photon-proton and proton-proton cross sections, for Q2<150 GeV2. In order to do so, one must postulate the existence of double-pole or triple-pole singularities in the complex j plane.

3 pages, 3 figures, to appear in the proceedings of the 31st International Conference on High Energy Physics (ICHEP 2002), Amsterdam, The Netherlands, 24-31 July 2002, needs espcrc2.sty

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