Theory HEP Seminar

Landau Singularities and the Geometry of On-shell Spaces

Hofie Hannesdottir

IAS

In this talk, we present several classes of constraints on the allowed singularity structure and sequential discontinuities of Feynman integrals. While some of the relations are generic, others present simplifications for polylogarithmic integrals, and yet others constrain amplitudes in physical-kinematic regions. We show how these relations follow from a geometric formulation of the Landau equations, in which the singularities of Feynman integrals correspond to critical points of maps between on-shell spaces, as well as expansions of Feynman integrals around their branch points.