Foliated structure of weak nearly Sasakian manifolds

Abstract: Weak contact metric manifolds, i.e., the linear complex structure on the contact distribution is replaced by a nonsingular skew-symmetric tensor, defined by the author and R. Wolak, allowed a new look at the theory of contact manifolds. In this paper we study the new structure of this type, called the weak nearly Sasakian structure. We find conditions that are automatically satisfied by almost contact manifolds and under which the contact distribution is curvature invariant and the weak nearly Sasakian structure foliates into two types of totally geodesic foliations. Our main result generalizes the theorem by B. Cappelletti-Montano and G. Dileo (2016) about the foliated structure of nearly Sasakian manifolds.