Almost Kenmotsu manifolds admitting certain vector fields

Abstract

In the present paper, we characterize almost Kenmotsu manifolds admitting holomorphically planar conformal vector (HPCV) fields. We have shown that if an almost Kenmotsu manifold $M^{2n+1}$ admits a non-zero HPCV field $V$ such that $\varphi V=0$, then $M^{2n+1}$ is locally a warped product of an almost Kaehler manifold and an open interval. As a corollary of this we obtain few classifications of an almost Kenmotsu manifold to be a Kenmotsu manifold and also prove that the integral manifolds of D are totally umbilical submanifolds of $M^{2n+1}$. Further, we prove that if an almost Kenmotsu manifold with positive constant $\xi$-sectional curvature admits a non-zero HPCV field $V$, then either $M^{2n+1}$ is locally a warped product of an almost Kaehler manifold and an open interval or isometric to a sphere. Moreover, a $(k,\mu {)}^{\prime }$-almost Kenmotsu manifold admitting a HPCV field $V$ such that $\varphi V=0$ is either locally isometric to ${\mathbb{H}}^{n+1}(-4)\times {\mathbb{R}}^n$ or $V$ is an eigenvector of $h^{\prime }$. Finally, an example is presented.

10 pages