Ricci-Flat and Charged Wormholes in Five Dimensions
  We construct stationary Ricci-flat inter-universe Lorentzian wormhole solutions in all D\ge 5 dimensions that connect two flat asymptotic spacetimes. Such a solution can be viewed as the gravity dual of a string tachyon state whose linear momentum is larger than its tension. We focus our analysis on the D=5 wormholes which are not traversable for the timelike and null geodesics; however, we demonstrate that there exist accelerated timelike trajectories that traverse from one asymptotic region to the other. We further study the minimally-coupled scalar wave equation and demonstrate that the quantum tunnelling between two worlds must occur. We also obtain charged wormholes in five-dimensional supergravities. With appropriate choice of parameters, these wormholes connect AdS$_3\times S^2$ in one asymptotic region to flat Minkowskian spacetime in the other. 
H. Lu and Jianwei Mei