Split reductions of simple abelian varieties
arXiv:0806.4421 · doi:10.4310/MRL.2009.v16.n2.a1
Abstract
Consider an absolutely simple abelian variety X over a number field K. If the absolute endomorphism ring of X is commutative and satisfies certain parity conditions, then the reduction X_p is absolutely simple for almost all p. Conversely, if the absolute endomorphism ring of X is noncommutative, then X_p is reducible for p in a set of positive density.
14 pages