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Résumé |
Infrared divergences obscure key analytic properties of scattering amplitudes, exposing gaps in our understanding of unitarity, causality, and crossing symmetry in theories with long-range forces. In this talk, I will use a simple model to illustrate novel analytic features of long-range theories, including modifications to the connectedness structure of amplitudes and to the general optical theorem. Since the LSZ reduction formula does not apply to theories with long-range forces, I will also present a modified version of LSZ reduction for this model, which accounts for long-range interactions and yields IR-finite amplitudes without ambiguous scales or ill-defined integrals. |
