K3 surfaces with non-symplectic involution and compact irreducible G_2-manifolds
Abstract
We consider the connected-sum method of constructing compact Riemannian 7-manifolds with holonomy G_2 developed in math.DG/0012189. The method requires pairs of projective complex threefolds endowed with anticanonical K3 divisors, the latter `matching' via a certain non-holomorphic map. Suitable examples of threefolds were previously obtained in math.DG/0012189 by blowing up curves in Fano threefolds. In this paper, we give further suitable algebraic threefolds using theory of K3 surfaces with non-symplectic involution due to Nikulin. These threefolds are not obtainable from Fano threefolds, as above, and admit matching pairs leading to topologically new examples of compact irreducible G_2-manifolds. `Geography' of the values of Betti numbers b^2,b^3 for the new (and previously known) examples of compact irreducible G_2 manifolds is also discussed.
Keywords
Cite
@article{arxiv.0810.0957,
title = {K3 surfaces with non-symplectic involution and compact irreducible G_2-manifolds},
author = {Alexei Kovalev and Nam-Hoon Lee},
journal= {arXiv preprint arXiv:0810.0957},
year = {2011}
}
Comments
30 pages; v2: misprint in the abstract corrected (no changes in the paper); v3: formula for b^3(M) in Theorem 2.5 corrected, respective computations of examples revised, some arguments expanded, references added; v4: enhancements in Theorem 5.3, new Proposition 5.5, more examples, presentation improved