Local heuristics and an exact formula for abelian varieties of odd prime dimension over finite fields
Jonathan Gerhard, Cassie Williams · arXiv (Cornell University) · 2017
Consider a $q$-Weil polynomial $f$ of degree $2g$. Using an equidistribution assumption that is too strong to be true, we define and compute a product of local relative densities of matrices in $\\rm{GSp}_{2g}(\\mathbb{F}_\\ell)$ with characteristic polynomial $f\\mod\\ell$ when $g$ is an odd prime. This infinite product is closely related to a ratio of class numbers. When $g=3$ we conjecture that the product gives the size of an isogeny class of principally polarized abelian threefolds.