Relativistic Field Theories for Interacting Classical Higher-Spin Particles

by Radu Roiban

Friday 8 May 2026, 12:30 → 14:30 America/Los_Angeles

48/2-224 - Madrone (SLAC)

The construction of an effective field theory describing the long-distance interactions of Kerr black holes remains elusive.
As a step in its direction, we discuss relativistic effective field theories designed to capture the long-distance gravitational interactions of massive spinning particles. While "no-go" theorems severely constrain the formulation of interacting higher-spin theories, we argue that these challenges can be navigated in the classical limit through the use of spin coherent states.
These states naturally incorporate gapless excitations which turn out to provide a description for processes in which the magnitude of the spin vector evolves dynamically.
We show that, by appropriately choosing the couplings of the theory, these modes can either be decoupled or tuned to describe specific systems. We discuss the broader applicability of this framework, showing that it captures certain supersymmetric black holes as well as the dynamics of Newtonian bound states under external probes. Finally, we discuss possible strategies to identify the definition of Kerr black holes in this framework.

SLAC_2026.pptx