Inherited twistor-space structure of gravity amplitudes

At tree-level, gravity amplitudes are obtainable directly from gauge theory amplitudes via the Kawai, Lewellen and Tye closed-open string relations. We explain how the unitarity method allows us to use these relations to obtain coefficients of box integrals appearing in one-loop N = 8 supergravity amplitudes from the recent computation of the coefficients for N = 4 super-Yang-Mills non-maximally-helicity-violating amplitudes. We argue from factorisation that these box coefficients determine the one-loop N = 8 supergravity amplitudes, although this remains to be proven. We also show that twistor-space properties of the N = 8 supergravity amplitudes are inherited from the corresponding properties of N = 4 super-Yang-Mills theory. We give a number of examples illustrating these ideas.