Rigidity of noncompact complete manifolds with harmonic curvature

Abstract

Let $(M,g)$ be a noncompact complete $n$-manifold with harmonic curvature and positive Sobolev constant. Assume that $L_2$ norms of Weyl curvature and traceless Ricci curvature are finite. We prove that $(M,g)$ is Einstein if $n\ge 5$ and $L_{n/2}$ norms of Weyl curvature and traceless Ricci curvature are small enough.

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