Black rings at large D

We study the effective theory of slowly rotating black holes at the infinite limit of the spacetime dimension d. this large d effective theory is obtained by integrating the einstein equation with respect to the radial direction. the effective theory gives equations for non-linear dynamical deformations of a slowly rotating black hole by effective equations. the effective equations contain the slowly rotating myers-perry black hole, slowly boosted black string, non-uniform black string and black ring as stationary solutions. we obtain the analytic solution of the black ring by solving effective equations. furthermore, by perturbation analysis of effective equations, we find a quasinormal mode condition of the black ring in analytic way. as a result we confirm that thin black ring is unstable against non-axisymmetric perturbations. we also include 1/d corrections to the effective equations and discuss the effects by 1/d corrections.