On-Shell Perspectives on the Massless Limit of Massive Supergravity

Understand

Massive gravity exhibits a famous discontinuity in its 2-point linearized amplitude for t-channel scattering of gravitational sources, in the $m \to 0$ limit.

• In essence, the source of this vDVZ discontinuity is in the failure of the zero-helicity mode to decouple in this limit.
• In [1], we showed how this result could be understood in the context of modern on-shell methods and, in particular, the BCFW construction.
• In this article, we provide a similar on-shell perspective to the equally interesting but lesser known discontinuity first discovered by Deser, Kay and Stelle in massive supergravity.