Transverse totally geodesic submanifolds of the tangent bundle

Abstract

It is well-known that if $\xi$ is a smooth vector field on a given Riemannian manifold $M^n$ then $\xi$ naturally defines a submanifold $\xi (M^n)$ transverse to the fibers of the tangent bundle $T{M}^n$ with Sasaki metric. In this paper, we are interested in transverse totally geodesic submanifolds of the tangent bundle. We show that a transverse submanifold $N^l$ of $T{M}^n$ ($1\le l\le n$) can be realized locally as the image of a submanifold $F^l$ of $M^n$ under some vector field $\xi$ defined along $F^l$. For such images $\xi (F^l)$, the conditions to be totally geodesic are presented. We show that these conditions are not so rigid as in the case of $l=n$, and we treat several special cases ($\xi$ of constant length, $\xi$ normal to $F^l$, $M^n$ of constant curvature, $M^n$ a Lie group and $\xi$ a left invariant vector field)