Two loops in eleven dimensions
Two loops in eleven dimensions
The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus $\mathcal{T}{}^{2}$ is analyzed in detail. The Schwinger parameter integrations are reexpressed as an integration over the moduli space of a second torus $\mathcal{T\ifmmode \hat{}\else \^{}\fi{}}{}^{2},$ which enables the leading low-momentum contribution to be evaluated …