Gabriele Casagrande, "A unique coupling of the massive spin-2 field to supergravity"

ITMP seminar, Apr 16, 2025

Speaker: Gabriele Casagrande, École Polytechnique, CNRS

Title: A unique coupling of the massive spin-2 field to supergravity
Abstract: In this talk, I will discuss the coupling of a massive spin-2 field to (undeformed) D=4, N=1 supergravity. We analyze this coupling by constructing the general stress-energy tensor multiplet for the N=1 massive spin-2 supermultiplet. We show that, at leading order in the Planck mass, this coupling is unique and characterized by a specific non-minimal coupling to the Riemann tensor. The massive spin-2 sector of this unique coupling reproduces the one of an oscillator mode in open string theory. The massive spin-1 sector, on the other hand, includes a higher-derivative term that may lead to violations of causality, which can be resolved by introducing infinitely many higher-spin fields, similar to the Regge trajectories in string theory. Moreover, we argue that this coupling is genuinely different from the one arising from Kaluza-Klein reductions of higher-dimensional supergravities, which we show leads instead to a deformation of the massless supersymmetry transformations.