Soft theorems from on-shell amplitudes

by Adam Falkowski (Universite Paris-Saclay)

Thursday 4 Mar 2021, 12:00 → 13:00 Europe/Madrid

IFAE Virtual Seminar Room (IFAE)

Soft theorems play an important role in quantum field theory, controlling the infrared behavior of gauge and gravity theories. In the standard approach, soft theorems follow from gauge invariance. More recently, soft theorems have been formulated in the on-shell amplitude language. In this framework, they allow one to derive certain universal properties of gauge and gravity theories, such as charge conservation or the equivalence principle, without ever introducing gauge invariance.  In this talk I will review the on-shell approach to soft theorems, and discuss some of its novel applications for massive particles of any spin. This approach leads, in particular, to new results regarding interactions of massive matter with photons and gravitons, and to a convenient representation of the Compton scattering amplitude for any mass and spin.