Mediterranean Journal of Mathematics, vol.20, no.3, 2023 (SCI-Expanded)
In this paper, we prove that the harmonicity of a metric on a pseudo-Riemannian manifold is equivalent to the harmonicity of both its Sasaki (resp. complete) lift metric on the tangent bundle and its Sasaki lift metric (resp. the Riemannian extension of the Levi-Civita connection) on the cotangent bundle, meanwhile we deal with harmonic metrics on warped product spaces. Some applications are included.