On the low energy limit of one loop photon-graviton amplitudes
  We present first results of a systematic study of the structure of the low energy limit of the one-loop photon-graviton amplitudes induced by massive scalars and spinors. Our main objective is the search of KLT-type relations where effectively two photons merge into a graviton. We find such a relation at the graviton-photon-photon level. We also derive the diffeomorphism Ward identity for the 1PI one graviton - N photon amplitudes. 
F. Bastianelli, O. Corradini, J. M. Davila, C. Schubert
hep-th gr-qc