1208.1255 (Piotr Tourkine et al.)

One-loop four-graviton amplitudes in N=4 supergravity models    [PDF]

Piotr Tourkine, Pierre Vanhove

We evaluate with great details one-loop four-graviton field theory amplitudes in pure N=4 D=4 supergravity. The expressions are obtained by taking the field theory limit of (4,0) and (2,2) string theory models. For each model we extract the contributions of the spin 1 and spin 2 N=4 supermultiplets running in the loop. We show that all the string based constructions with (4,0) symmetry lead to the same answer as the one derived by unitarity and double-copy method in field theory. But the limit of the string theory (2,2) models leads to a different answer, that we attribute to the different nature of the vector multiplet couplings.

View original: http://arxiv.org/abs/1208.1255