derivative of g with respect to r the torsion introduced by Chern-Hamilton [6]. In [10](see also
[9]) we gave a variational characterization of compact contact Riemannian manifolds which
satisfy the condition (*) v~ r= 0 where V is the Levi-Civita connection of g. We refer to [10]
and [9] for the motivation of the study of the condition (*). Classically a large class of contact
metric manifolds is formed by the tangent sphere bundles of Riemannian manifolds. Let (r …