Supergravity and theSmatrix

Abstract

We discuss rupergravity from an S-matrix point of view. Kinematical constraints on helicity amplitudes determine the spin-2 and spin-3/2 Born amplitudes almos! uniquely, and force Born ar.lplitudes in~olving spin-5 / 2 fermions to vanish. Global supersymmetry is then used to determine the Born amplitudes con~pletely. We suggest that Lorentz invariance, presence of only one (dimensional) coupling io!~stdiit K, and global supersymmetry lead to a unique locally supergauge-invnrii~!~~ theory of spin-2 and spin-3/2 particles. We draw similar conclusions for a model uniting supergmvity and the Wess-Zurnino scalar multiplrt.

Two-loop self-dual Euler-Heisenberg Lagrangians (I): Real part and helicity amplitudes

“…The one-loop relation (5.19) is a direct consequence of the supersymmetry Ward identities for S-matrix elements first obtained by Grisaru, Pendleton and van Nieuwenhuizen [69,70]. Those identities hold for massive as well as for massless supermultiplets in the loop.…”

One-loop splitting amplitudes in gauge theory

“…If we set n f /N → 1 and 1/N 2 → −1, we obtain the corresponding quantities in a supersymmetric theory. These latter satisfy various identities descended from the supersymmetry Ward identity [21]. Such identities thus provide a cross-check on the splitting amplitudes even in nonsupersymmetric theories such as QCD.…”

Monodromy-like relations for finite loop amplitudes

“…. , n + ) = 0, colorordered amplitudes with quarks circulating the loop are equal, up to a sign, to the colorordered amplitudes having only gluons in the loop [39]. Instead of eq.…”