English

A birational Torelli theorem with a Brauer class

Algebraic Geometry 2019-09-13 v1

Abstract

Let MC(2,OC)P3\text{M}_C( 2, \mathcal{O}_C) \cong \mathbb{P}^3 denote the coarse moduli space of semistable vector bundles of rank 22 with trivial determinant over a smooth projective curve CC of genus 22 over C\mathbb{C}. Let βC\beta_C denote the natural Brauer class over the stable locus. We prove that if f(βC)=βCf^*( \beta_{C'}) = \beta_C for some birational map ff from MC(2,OC)\text{M}_C( 2, \mathcal{O}_C) to MC(2,OC)\text{M}_{C'}( 2, \mathcal{O}_{C'}), then the Jacobians of CC and of CC' are isomorphic as abelian varieties. If moreover these Jacobians do not admit real multiplication, then the curves CC and CC' are isomorphic. Similar statements hold for Kummer surfaces in P3\mathbb{P}^3 and for quadratic line complexes.

Keywords

Cite

@article{arxiv.1909.05541,
  title  = {A birational Torelli theorem with a Brauer class},
  author = {Norbert Hoffmann and Fabian Reede},
  journal= {arXiv preprint arXiv:1909.05541},
  year   = {2019}
}

Comments

15 pages

R2 v1 2026-06-23T11:13:14.410Z