Lorenz Eberhardt

I will describe a method to compute one-loop string scattering amplitudes at finite energies. Inspired by methods in analytic number theory, it rewrites the modular integral as an infinite series controlled by Lorentzian degeneration singularities in moduli space. I will illustrate the method for the type II one-loop four-graviton amplitude and discuss its physical content, with emphasis on the high-energy limit. In particular, I will show that the Gross–Mende saddle-point picture must be refined to include complex saddle points in order to reproduce the correct one-loop asymptotics. This talk is based on joint works with M.M. Baccianti, J. Chandra, T. Hartman and S. Mizera. Zoom link: https://belgrade-strings-ipb-ac-rs.zoom.us/j/6664242666?pwd=QW5UjVWFuadA4MBhB0K6wockM1OxPZ.1&omn=92396080924 Meeting ID: 666 4242 666 Passcode: 314159