A lower bound of the energy functional of a class of vector fields and a characterization of the sphere

Giovanni da Silva Nunes, Jaime Ripoll

Let $M$ be a compact, orientable, $n$-dimensional Riemannian manifold, $n\ge 2$, and let $F$ be the energy functional acting on the space $\Xi (M)$ of $C^{\infty }$ vector fields of $…