Commuting Structure Jacobi Operator for Semi-Invariant Submanifolds of Codimension 3 in Complex Space Forms
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Let M be a semi-invariant submanifold with almost contact metric structure (φ,ξ,η,g) of codimension 3 in a complex space form Mn+1(c),c ̸= 0. We denote by S and Rξ be the Ricci tensor of M and the structure Jacobi operator in the direction of the structure vec- tor ξ, respectively. Suppose that the third fundamental form t satisfies dt(X, Y ) = 2θg(φX, Y ) for a certain scalar θ(̸= 2c) and any vector fields X and Y on M. In this paper, we prove that M satisfies RξS = SRξ and at the same time Rξφ = φRξ, then M is a Hopf hypersurface of type (A) provided that the scalar curvature s of M holds s − 2(n − 1)c ≤ 0.
Abstract
Let M be a semi-invariant submanifold with almost contact metric structure (φ,ξ,η,g) of codimension 3 in a complex space form Mn+1(c),c ̸= 0. We denote by S and Rξ be the Ricci tensor of M and the structure Jacobi operator in the direction of the structure vec- tor ξ, respectively. Suppose that the third fundamental form t satisfies dt(X, Y ) = 2θg(φX, Y ) for a certain scalar θ(̸= 2c) and any vector fields X and Y on M. In this paper, we prove that M satisfies RξS = SRξ and at the same time Rξφ = φRξ, then M is a Hopf hypersurface of type (A) provided that the scalar curvature s of M holds s − 2(n − 1)c ≤ 0.
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