Static and symmetric wormholes respecting energy conditions in Einstein-Gauss-Bonnet gravity

Properties of n(>= 5)-dimensional static wormhole solutions are investigated in Einstein-Gauss-Bonnet gravity with or without a cosmological constant Lambda. We assume that the spacetime has symmetries corresponding to the isometries of an (n-2)-dimensional maximally symmetric space with the sectional curvature k=+/- 1, 0. It is also assumed that the metric is at least C-2 and the (n-2)-dimensional maximally symmetric subspace is compact. Depending on the existence or absence of the general relativistic limit alpha -> 0, solutions are classified into general relativistic (GR) and non-GR branches, respectively, where alpha is the Gauss-Bonnet coupling constant. We show that a wormhole throat respecting the dominant energy condition coincides with a branch surface in the GR branch, otherwise the null energy condition is violated there. In the non-GR branch, it is shown that there is no wormhole solution for k alpha >= 0. For the matter field with zero tangential pressure, it is also shown in the non-GR branch with k alpha < 0 and Lambda <= 0 that the dominant energy condition holds at the wormhole throat if the radius of the throat satisfies some inequality. In the vacuum case, a fine-tuning of the coupling constants is shown to be necessary and the radius of a wormhole throat is fixed. Explicit wormhole solutions respecting the energy conditions in the whole spacetime are obtained in the vacuum and dust cases with k=-1 and alpha > 0.