Particle Theory Seminar - Michael Saavedra - University of California, Los Angeles

Classical Gravitational Scattering to All Orders at High Energies

It has long been known that perturbation theory breaks down for the gravitational scattering of two classical massive bodies at ultrarelativistic velocities, and that restoring calculational control requires a resummation of perturbation theory. This stands in contrast to the case of massless scattering, where perturbation theory is expected to hold. In this talk, I use tools from effective field theory to discuss the relation between these two regimes, and show how the breakdown of perturbation theory emerges. Moreover, I show how one may identify and then resum the leading perturbative contributions.

Biography: Michael Saavedra is a postdoctoral scholar at the Mani L. Bhaumik Institute for Theoretical Physics at UCLA. He works on scattering amplitudes and effective field theory, with applications to gravitational waves and particle physics. He received his PhD from Carnegie Mellon in 2025.

Host: Ian Moult