Asymptotic symmetries and subleading soft graviton theorem in higher dimensions

We investigate the relation between the subleading soft graviton theorem and asymptotic symmetries in gravity in even dimensions higher than four. After rewriting the subleading soft graviton theorem as a Ward identity, we argue that the charges of such identity generate Diff$(S^{2m})$. In order to show that, we propose suitable commutation relation among certain components of the metric fields. As a result, all Diff$(S^{2m})$ transformations are symmetries of gravitational scattering.