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arXiv · 2109.05147

Finiteness of reductions of Hecke orbits

Mark Kisin·Yeuk Hay Joshua Lam·Ananth N. Shankar·Padmavathi Srinivasan
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Abstract

We prove two finiteness results for reductions of Hecke orbits of abelian varieties over local fields: one in the case of supersingular reduction and one in the case of reductive monodromy. As an application, we show that only finitely many abelian varieties on a fixed isogeny leaf admit CM lifts, which in particular implies that in each fixed dimension $g$ only finitely many supersingular abelian varieties admit CM lifts. Combining this with the Kuga-Satake construction, we also show that only finitely many supersingular $K3$-surfaces admit CM lifts. Our tools include $p$-adic Hodge theory and group theoretic techniques.

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Mark Kisin, Yeuk Hay Joshua Lam, Ananth N. Shankar, Padmavathi Srinivasan. 2021-09-11. Finiteness of reductions of Hecke orbits. https://arxiv.org/abs/2109.05147

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