A remark on left invariant metrics on compact Lie groups
arXiv:0705.0985
Abstract
We show that a left invariant metric on a compact Lie group which is obtained by stretching a biinvariant metric in the direction of a subalgebra $\h$ of $\g$ always has some negative sectional curvature, unless the semi-simple part of $\h$ is an ideal of $\g$.
4 pages