PU High Energy Theory Seminar

Abstract: Progress in recent years on the S-matrix bootstrap and bottom-up constructions of candidate string theory amplitudes, have brought about a revival of interest in the so-called Coon amplitude: a q-deformed generalization of the Veneziano amplitude exhibiting a semi-infinite sequence of poles that converge on an accumulation point, from which a branch cut emerges.

This seminar provides a friendly overview of q-deformed string amplitudes and their appeal, surveying the compelling indications that have emerged in recent years that the Coon amplitude satisfies the stringent constraints imposed by locality and unitarity, and reviewing attempts at a physical interpretation. But we will also see that the Coon amplitude in its branch cut actually hides some well-concealed violations of the positivity requirements imposed by unitarity.