Characterization of torus quotients

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Let XX be a compact complex space of dimension n≥2n\geq 2. Let c~2(X)\widetilde{c}_2(X) denote the second orbifold Chern class of XX, and let a finite group action be free in codimension one when its non-free locus has codimension at least two. Characterization of torus quotients. The following are equivalent:

  1. XX has klt singularities, c1(X)=0∈H2(X,R)c_1(X)=0\in H^2(X,\mathbb{R}), and there exists a Kähler class ω∈H2(X,R)\omega\in H^2(X,\mathbb{R}) such that
c~2(X)⋅ωn−2=0.\widetilde{c}_2(X)\cdot\omega^{n-2}=0.
  1. There exists a complex torus TT and a holomorphic action of a finite group GG on TT, free in codimension one, such that
X≅T/G.X\cong T/G.

In dimension 22, this characterization is well known. In dimension 33, it would follow from the stated three-dimensional result together with the relevant special case of the Abundance Conjecture; the general statement in dimensions n≥2n\geq 2 remains open.

References

Primary source

Patrick Graf and Tim Kirschner, “Finite quotients of three-dimensional complex tori”, arXiv:1701.04749 (2017).

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