Rademacher evaluation of one-loop string amplitudes [FOR Virtual Seminar]

by Lorenz Eberhardt (University of Amsterdam)

Wednesday Jun 18, 2025, 11:00 AM → 1:00 PM Europe/Berlin

 I will explain a general technique that evaluates one-loop string amplitudes exactly in terms of an infinite series originating from certain Lorentzian singularities in moduli space. For the open string, this amounts to a rather direct application of the classical Rademacher procedure developed in the context of analytic number theory. For the closed string I will explain a non-holomorphic extension of the Rademacher procedure that applies to any integral of a modular function (with certain boundedness conditions). I will then discuss the concrete example of the one-loop four-graviton scattering amplitude for type II superstrings and the physics we can extract from these methods. This talk is based on joint work with M.M. Baccianti, J. Chandra, T. Hartman and S. Mizera.