Transcendental splitting fields of division algebras

TL;DR

This paper investigates the properties of division algebras sharing common splitting fields, revealing conditions under which infinite classes exist and establishing finiteness results for division algebras with shared low-transcendence splitting fields.

Contribution

It demonstrates the existence of infinitely many nonisomorphic division algebras with identical finite and transcendence degree 1 splitting fields, and proves finiteness of such algebras for transcendence degrees up to 3.

Findings

Existence of infinitely many nonisomorphic division algebras with the same set of splitting fields.

Finiteness of division algebras sharing splitting fields of transcendence degree at most 3.

Finiteness of division algebras sharing splitting fields of transcendence degree at most 2.

Abstract

We examine when division algebras can share common splitting fields of certain types. In particular, we show that one can find fields for which one has infinitely many Brauer classes of the same index and period at least 3, all nonisomorphic and having the same set of finite splitting fields as well as the same splitting fields of transcendence degree $1$ and genus at most $1$. On the other hand, we show that one fixes any division algebra over a field, then any division algebras sharing the same splitting fields of transcendence degree at most 3 must generate the same cyclic subgroup of the Brauer group. In particular, there are only a finite number of such division algebras. We also show that a similar finiteness statement holds for splitting fields of transcendence degree at most $2$.