HyperKahler contact Distribution in 3-Sasakain Manifolds
  In this paper, the HyperKahler contact distribution of a 3-Sasakian manifold is studied. To analyze the curvature properties of this distribution, the special metric connection $\bar{\nabla}$ is defined. This metric connection is completely determined by HyperKahler contact distribution. We prove that HyperKahler contact distribution is of constant holomorphic sectional curvatures if and only if its 3-Sasakian manifold is of constant $\varphi_{\alpha}$-sectional curvatures. Moreover, it is shown that there is an interesting relation between the sectional curvatures of $\varphi_{\alpha}$-planes on $TM$ of metric connection $\bar{\nabla}$ and the Levi-Civita connection. 
M. M. Rezaii, H. Attarchi and F. Babaei
math.MG math.DG