arXiv subjects
Publications and source records attributed to Moritz Hartlieb.
Following ideas of Kapustka-Kapustka, we use Lagrangian fibrations to construct twisted hyperholomorphic sheaves on products of hyperk\"ahler manifolds of K3$^{[n]}$- and OG10-type. As applications, we prove the Lefschetz standard conjecture and the D-equivalence conjecture for hyperk\"ahler manifolds of OG10-type.
We study Brauer groups of the smooth loci in linear systems on simply connected smooth projective varieties. Under a suitable ampleness condition, we prove that the Brauer group is at most $\mathbb Z/2 \mathbb Z$. This applies when the underlying variety is the projective plane, a very general K3 surface, or a general cubic fourfold. As an application, we compute the Tate--Shafarevich group parametrizing torsors over the relative Jacobians of universal smooth plane curves. Our approach is via a study of the $2$-nodal locus in the linear system.
In this note, we generalize results of Donagi and Pantev on twisted derived equivalences between elliptically fibered surfaces to higher dimensions. First, we establish a twisted derived equivalence between torsors under abelian schemes satisfying a certain compatibility condition. Then, relying on the work of Arinkin on compactified Jacobians, we extend the equivalence to twisted compactified Jacobians associated to curves on K3 surfaces. This positively answers a question stated by Mattei and Meinsma. We then extend a result of Bottini and Huybrechts for Fano varieties of lines on cubic fourfolds to general moduli spaces of Bridgeland-stable objects on Kuznetsov components admitting rational Lagrangian fibrations.
We study the topological Brauer group of generalized Kummer varieties. We prove that it vanishes when their dimension is divisible by 4, while for all other dimensions except dimension 10 we prove that it is at most 8-torsion.
We study the geometry, Hodge theory and derived category of cubic fourfolds containing several planes and their associated twisted K3 surfaces. We focus on the case of two planes intersecting along a line.
We study special subvarieties, i.e., subvarieties containing a dense subset of CM points, of the moduli space $A_5$ of principally polarized abelian varieties of dimension five, generically contained in the locus of intermediate Jacobians of cubic threefolds. The analogous question for Jacobians of curves is related to a conjecture of Coleman-Ort and has been studied by Shimura, Mostow, De Jong-Noot, Rohde, Moonen, Oort, Frediani, Ghigi and others. Adapting methods of Frediani, Ghigi and Penegini, we give a sufficient condition ensuring that the closure of the image of a family of smooth cubic threefolds with prescribed automorphisms via the period map is a special subvariety of $A_5$. By the work of Allcock, Carlson and Toledo, it is known that the family of cyclic cubic threefolds gives rise to a special subvariety. Analyzing the action of subgroups of the automorphism group of the Klein cubic threefold, we discover new examples of positive-dimensional special subvarieties arising from families of smooth cubic threefolds that are not contained in the locus of cyclic cubic threefolds.