Constructible tori over Dedekind schemes
Adrien Morin, Takashi Suzuki
TL;DR
The paper develops a duality between torsion-free constructible tori over a Dedekind scheme $X$ and torsion-free $\mathbb{Z}$-constructible sheaves, realized through two-term complexes and Cartier duality. It then systematically builds a derived framework of constructible tori, including a robust notion of duals, biduality, and an abelian category of constructible tori with torsion, establishing a functorial determinant theory via det Lie and its extensions. Using these foundations, the authors define $L$-functions for constructible tori via their étale realizations and prove a Weil-étale special value formula at $s=0$, extending prior tame-ramification results. The work unifies local-to-global determinant identities, multiplicativity under exact sequences, Weil restriction behavior, and pushforward properties, providing a comprehensive toolkit for studying arithmetic invariants of tori on Dedekind schemes and their $L$-values.
Abstract
We introduce an exact category of torsion-free constructible tori and an abelian category of constructible tori over a Dedekind scheme with perfect residue fields. The first one has an explicit description as $2$-term complexes of smooth commutative group algebraic spaces. Using the second-named author's duality results arXiv:1806.07641, we prove that they are equivalent to the opposite of the categories of torsion-free $\mathbb{Z}$-constructible sheaves and all $\mathbb{Z}$-constructible sheaves, respectively. We then define $L$-functions for constructible tori over a Dedekind scheme proper over $\mathrm{Spec}(\mathbb{Z})$ in terms of their étale realizations and prove a special value formula at $s=0$ using the Weil-étale formalism developed by the first-named author in arXiv:2210.09102. This extends the results of the first-named author by removing the tame ramification hypothesis.
