Notes on Conformal Soft Theorems and Recursion Relations in Gravity

Understand

Celestial amplitudes are flat-space amplitudes which are Mellin-transformed to correlators living on the celestial sphere.

• In this note we present a recursion relation, based on a tree-level BCFW recursion, for gravitational celestial amplitudes and use it to explore the notion of conformal softness.
• As the BCFW formula exponentiates in the soft energy, it leads directly to conformal soft theorems in an exponential form.
• These appear from a soft piece of the amplitude characterized by a discrete family of singularities with weights $\Delta=1-\mathbb{Z}_+$.