A Modular Non-Rigid Calabi-Yau Threefold
arXiv:math/0508127
Abstract
We construct an algebraic variety by resolving singularities of a quintic Calabi-Yau threefold. The middle cohomology of the threefold is shown to contain a piece coming from a pair of elliptic surfaces. The resulting quotient is a two-dimensional Galois representation. By using the Lefschetz fixed-point theorem in étale cohomology and counting points on the variety over finite fields, this Galois representation is shown to be modular.
34 pages; To appear in "Mirror Symmetry V", Proceedings of the BIRS Workshop on Calabi-Yau Varieties and Mirror Symmetry, December 6-11, 2003. Some typos in tables corrected, proof of Lemma 5.6 corrected