Integral Cohomology and Mirror Symmetry for Calabi-Yau 3-folds
arXiv:math/0505432
Abstract
In this paper, we compute the integral cohomology groups for all examples of Calabi-Yau 3-folds obtained from hypersurfaces in 4-dimensional Gorenstein toric Fano varieties. Among 473 800 776 families of Calabi-Yau 3-folds corresponding to 4-dimensional reflexive polytopes there exist exactly 32 families having non-trivial torsion in . We came to an interesting observation that the torsion subgroups in and are exchanged by the mirror symmetry involution, i.e. the torsion subgroup in the Picard group of is isomorphic to the Brauer group of the mirror
18 pages, AMS-LaTeX