English

Non-commutative Iwasawa theory of abelian varieties over global function fields

Number Theory 2025-12-03 v2

Abstract

Let AA be an abelian variety defined over a global function field FF, and let pp be a prime distinct from the characteristic of FF. Let FF_\infty be a pp-adic Lie extension of FF that contains the cyclotomic Zp\mathbb{Z}_p-extension FcycF^{\mathrm{cyc}} of FF. In this paper, we investigate the structure of the pp-primary Selmer group Sel(A/F)\mathrm{Sel}(A/F_\infty) of AA over FF_\infty. We prove the MH(G)\mathfrak{M}_H(G)-conjecture for A/FA/F_\infty. Furthermore, we show that both the μ\mu-invariant of the Pontryagin dual of the Selmer group Sel(A/Fcyc)\mathrm{Sel}(A/F^\mathrm{cyc}) and the generalised μ\mu-invariant of the Pontryagin dual of the Selmer group Sel(A/F)\mathrm{Sel}(A/F_\infty) are zero, therby proving Mazur's conjecture for A/FA/F. We then relate the order of vanishing of the characteristic elements, evaluated at Artin representations, to the corank of the Selmer group of the corresponding twist of AA over the base field FF. Assuming the finiteness of the Tate-Shafarevich group, we establish that this corank equals the order of vanishing of the LL-function of A/FA/F at s=1s=1. Finally, we extend a theorem of Sechi - originally proved for elliptic curves without complex multiplication - to abelian varieties over global function fields. This is achieved by adapting the notion of generalised Euler characteristic, introduced by Zerbes for elliptic curves over number fields. This new invariant allows us, via Akashi series, to relate the generalised Euler characteristic of Sel(A/F)\mathrm{Sel}(A/F_\infty) to the Euler characteristic of Sel(A/Fcyc)\mathrm{Sel}(A/F^{\mathrm{cyc}}).

Keywords

Cite

@article{arxiv.2405.20963,
  title  = {Non-commutative Iwasawa theory of abelian varieties over global function fields},
  author = {Li-Tong Deng and Yukako Kezuka and Yong-Xiong Li and Meng Fai Lim},
  journal= {arXiv preprint arXiv:2405.20963},
  year   = {2025}
}

Comments

23 pages. Journal of the Australian Mathematical Society, to appear