An arithmetic zeta function respecting multiplicities

Abstract

In this paper, we study the arithmetic zeta function $$\mathscr{Z}_{\mathcal{X}}(s) = \prod_p \prod_{\substack{x \in \mathcal{X}_p \\ \text{closed}}} \Big( \frac{1}{1-|\kappa(x)|^{-s}} \Big)^{\mathfrak{m}_{p}(x)}$$ associated to a scheme $\mathcal{X}$ of finite type over $\mathbb{Z}$, where $\kappa(x)$ denotes the residue field and $\mathfrak{m}_{p}(x)$ the multiplicity of $x$ in $\mathcal{X}_p$. If $\mathcal{X}$ is defined over a finite field, then $\mathscr{Z}_{\mathcal{X}}$ appears naturally in the context of point counting with multiplicities. We prove that $\mathscr{Z}_{\mathcal{X}}$ admits a meromorphic continuation to $\{s \in \mathbb{C} \colon \mathrm{Re}(s) > \mathrm{dim}(\mathcal{X})-1/2\}$ and determine the order of its pole at $s = \mathrm{dim}(\mathcal{X})$. Finally, we relate $\mathscr{Z}_{\mathcal{X}}$ to a zeta function $\zeta_f$ encoding the residual factorization patterns of a polynomial $f$.