Cubic Subfields of Exceptional Simple Jordan Algebras

Abstract

Let $E/k$ be a cubic field extension and $J$ a simple exceptional Jordan algebra of degree 3 over $k$. Then $E$ is a reducing field of $J$ if and only if $E$ is isomorphic to a (maximal) subfield of some isotope of $J$. If $k$ has characteristic not 2 or 3 and contains the third roots of unity then every simple exceptional Jordan division algebra of degree 3 over $k$ contains a cyclic cubic subfield.