Recently, new soft graviton theorem proposed by Cachazo and Strominger has
inspired a lot of works. In this note, we use the KLT-formula to investigate
the theorem. We have shown how the soft behavior of color ordered Yang-Mills
amplitudes can be combined with KLT relation to give the soft behavior of
gravity amplitudes. As a byproduct, we find two nontrivial identities of the
KLT momentum kernel must hold.Comment: 25 page

Du, Yi-Jian

Feng, Bo

Fu, Chih-Hao

Wang, Yihong