47 research outputs found
Projections of del Pezzo surfaces and Calabi--Yau threefolds
We study the syzygetic structure of projections of del Pezzo surfaces in
order to construct singular Calabi-Yau threefolds. By smoothing those
threefolds, we obtain new examples of Calabi-Yau threefolds with Picard group
of rank 1. We also give an example of type II primitive contraction whose
exceptional divisor is the blow-up of the projective plane at a point.Comment: A table of known Calabi--Yau threefolds with Picard number 1 is
added, to appear in Advances in Geometr
Primitive contractions of Calabi-Yau threefolds II
We construct 16 new examples of Calabi--Yau threefolds with Picard group of
rank 1. Each of these examples is obtained by smoothing the image of a
primitive contraction with exceptional divisor being a del Pezzo surface of
degree 6, 7 or .Comment: 20 pages, to appear in JLM
On IHS fourfolds with
The present work is concerned with the study of four-dimensional irreducible
holomorphic symplectic manifolds with second Betti number . We describe
their birational geometry and their relations to EPW sextics.Comment: to appear in Michigan Math.
EPW Cubes
We construct a new 20-dimensional family of projective 6-dimensional
irreducible holomorphic symplectic manifolds. The elements of this family are
deformation equivalent with the Hilbert scheme of three points on a K3 surface
and are constructed as natural double covers of special codimension 3
subvarieties of the Grassmanian G(3,6). These codimension 3 subvarieties are
defined as Lagrangian degeneracy loci and their construction is parallel to
that of EPW sextics, we call them the EPW cubes. As a consequence we prove that
the moduli space of polarized IHS sixfolds of K3-type, Beauville-Bogomolov
degree 4 and divisibility 2 is unirational.Comment: minor corrections, 25 pages, to appear in J. Reine Angew. Mat