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Selmer stability for elliptic curves in Galois ℓ-extensions

2025/04/22 by Pathak, Siddhi, Ray, Anwesh
#11G05 #11R45 #FOS: Mathematics #Number Theory (math.NT)

paper · doi:10.48550/arxiv.2504.15945

Abstract

We study the behavior of Selmer groups of an elliptic curve E/ℚ in finite Galois extensions with prescribed Galois group. Fix a prime ℓ ≥ 5, a finite group G with #G = ℓn, and an elliptic curve E/ℚ with Sel_ℓ(E/ℚ) = 0 and surjective mod-ℓ Galois representation. We show that there exist infinitely many Galois extensions F/ℚ with Galois group Gal(F/ℚ) ≃ G for which the ℓ-Selmer group Sel_ℓ(E/F) also vanishes. We obtain an asymptotic lower bound for the number M(G, E; X) of such fields F with absolute discriminant |ΔF|≤ X, proving that there is an explicit constant δ>0 such that M(G, E; X) ≫ X^\frac1ℓn-1(ℓ - 1) (log X)δ- 1. The asymptotic for M(G, E; X) matches the conjectural count for all G-extensions F/ℚ for which |ΔF|≤ X, up to a power of log X. This demonstrates that Selmer stability is not a rare phenomenon.

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