Speaker
Description
Massive particles with spin two appear naturally in scenarios where spacetime has extra dimensions. We analyze the possible interactions between such particles from the perspective of causality and unitarity of the S-matrix, assuming a separation between their mass and the higher-spin ($J\geq 3$) scale $\Lambda$ that signals a more dramatic breakdown of effective field theory. We tame the explosion in tensor contractions using two techniques: superconvergence sum rules and novel "dual" amplitudes. Using a handful of these, for example, we show analytically that all three-point vertices must be proportional to the Einstein-Hilbert structure up to $1/\Lambda$ corrections. We investigate the resulting constraints on low-lying spectra and couplings.