Ward identities for superamplitudes

A bstract We introduce Ward identities for superamplitudes in D -dimensional N N -extended supergravities. These identities help to clarify the relation between linearized superinvariants and superamplitudes. The solutions of these Ward identities for an n -partice superamplitude take a simple universal form for half BPS and non-BPS amplitudes. These solutions involve arbitrary functions of spinor helicity and Grassmann variables for each of the n superparticles. The dimension of these functions at a given loop order is exactly the same as the dimension of the relevant superspace Lagrangians depending on half-BPS or non-BPS superfields, given by ( D − 2) L + 2 − N N or ( D − 2) L + 2 − 2N 2 N , respectively. This explains why soft limits predictions from superamplitudes and from superspace linearized superinvariants agree.