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Derived equivalence of elliptic K3 surfaces and Jacobians

Reinder Meinsma, Evgeny Shinder

Abstract

We present a detailed study of elliptic fibrations on Fourier-Mukai partners of K3 surfaces, which we call derived elliptic structures. We fully classify derived elliptic structures in terms of Hodge-theoretic data, similar to the Derived Torelli Theorem that describes Fourier-Mukai partners. In Picard rank two, derived elliptic structures are fully determined by the Lagrangian subgroups of the discriminant group. As a consequence, we prove that for a large class of Picard rank 2 elliptic K3 surfaces all Fourier-Mukai partners are Jacobians, and we partially extend this result to non-closed fields. We also show that there exist elliptic K3 surfaces with Fourier-Mukai partners which are not Jacobians of the original K3 surface. This gives a negative answer to a question raised by Hassett and Tschinkel.

Derived equivalence of elliptic K3 surfaces and Jacobians

Abstract

We present a detailed study of elliptic fibrations on Fourier-Mukai partners of K3 surfaces, which we call derived elliptic structures. We fully classify derived elliptic structures in terms of Hodge-theoretic data, similar to the Derived Torelli Theorem that describes Fourier-Mukai partners. In Picard rank two, derived elliptic structures are fully determined by the Lagrangian subgroups of the discriminant group. As a consequence, we prove that for a large class of Picard rank 2 elliptic K3 surfaces all Fourier-Mukai partners are Jacobians, and we partially extend this result to non-closed fields. We also show that there exist elliptic K3 surfaces with Fourier-Mukai partners which are not Jacobians of the original K3 surface. This gives a negative answer to a question raised by Hassett and Tschinkel.
Paper Structure (18 sections, 46 theorems, 73 equations)

This paper contains 18 sections, 46 theorems, 73 equations.

Key Result

Theorem 1.2

Let $X$ be an elliptic K3 surface of Picard rank 2. Let $t$ be the multisection index of $X$ and let $2d$ be the degree of a polarisation on $X$. Denote $m=\operatorname{gcd}(d,t)$.

Theorems & Definitions (102)

  • Theorem 1.2: See Corollaries \ref{['cor:HT-DJ']} and \ref{['cor:DE-count']}
  • Proposition 1.3
  • Lemma 2.1: Nik80
  • Theorem 2.2: Surjectivity of the Period Map
  • Theorem 2.3: Torelli Theorem for K3 Surfaces
  • Theorem 2.4: Derived Torelli Theorem
  • Theorem 2.5: Counting Formula
  • Definition 2.6
  • Lemma 2.7: SZ20
  • Lemma 2.8: Cal00
  • ...and 92 more