On-shell recursion relations for generic theories

Abstract

We show that on-shell recursion relations hold for tree amplitudes in generic two derivative theories in an arbitrary number of dimensions with multiple particle species and diverse spins. For example, in a gauge theory coupled to scalars and fermions, any amplitude with at least one gluon obeys a recursion relation. In (super)gravity coupled to scalars and fermions, the same holds for any amplitude with at least one graviton. This result pertains to a broad class of theories, including QCD, N = 4 SYM, and N = 8 supergravity.