Klt varieties with semipositive anticanonical bundle : symmetric tensors, holonomy and structure

Source abstract

The aim of this article is to study klt projective varieties such that the anticanonical bundle is semipositive from the differential-geometric point of view. The study of the holonomy of such varieties yields generalizations of several results. We show that the dimension of the space of symmetric differentials is bounded by a constant depending on the augmented irregularity, generalizing a result of Kobayashi. If we endow such a variety $X$ with a metric $ω$ whose Ricci curvature is non-negative, then we show that the holonomy of the regular locus is compact. If we assume that $X$ has canonical singularities, then we show that the general fiber of the Albanese map can be decomposed into a product of irreducible Calabi-Yau varieties, irreducible holomorphic symplectic varieties and hereditarily rationally connected varieties by the holonomy generalizing a structure theorem of Campana, Demailly and Peternell. To conclude, we show that the fundamental group of the regular locus of such varieties is virtually abelian.