NONCOMMUTATIVE IWASAWA THEORY OF ABELIAN VARIETIES OVER GLOBAL FUNCTION FIELDS

Abstract Let A be an abelian variety defined over a global function field F and let p be a prime distinct from the characteristic of F . Let $F_\infty $ be a p -adic Lie extension of F that contains the cyclotomic $\mathbb {Z}_p$ -extension $F^{\mathrm {cyc}}$ of F . In this paper, we investigate the structure of the p -primary Selmer group $\mathrm {Sel}(A/F_\infty )$ of A over $F_\infty $ . We prove the $\mathfrak {M}_H(G)$ -conjecture for $A/F_\infty $ . Furthermore, we show that both the $\mu $ -invariant of the Pontryagin dual of the Selmer group $\mathrm {Sel}(A/F^{\mathrm {cyc}})$ and the generalized $\mu $ -invariant of the Pontryagin dual of the Selmer group $\mathrm {Sel}(A/F_\infty )$ are zero, thereby proving Mazur’s conjecture for $A/F$ . 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 A over the base field F . Assuming the finiteness of the Tate–Shafarevich group, we establish that this corank equals the order of vanishing of the L -function of $A/F$ at $s=1$ . 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 generalized Euler characteristic, introduced by Zerbes for elliptic curves over number fields. This new invariant allows us, via Akashi series, to relate the generalized Euler characteristic of $\mathrm {Sel}(A/F_\infty )$ to the Euler characteristic of $\mathrm {Sel}(A/F^{\mathrm {cyc}})$ .