The Standard Model Gauge Group from the Exceptional Jordan Algebra

Abstract

We construct the Standard Model gauge group using the exceptional Jordan algebra $\mathfrak{h}_3(\mathbb{O})$ and its automorphism group $\text{F}_4$. The group $\text{F}_4$ acts on pairs of Jordan subalgebras $X \subset B \subset \mathfrak{h}_3(\mathbb{O})$ with $X \cong \mathfrak{h}_2(\mathbb{C})$ and $B \cong \mathfrak{h}_3(\mathbb{C})$, and for any such pair the stabilizer of $X$ intersected with the identity component of the stabilizer of $B$ is isomorphic to the Standard Model gauge group. Since $\mathfrak{h}_2(\mathbb{C})$ is the Jordan algebra of observables of a qubit and $\mathfrak{h}_3(\mathbb{C})$ is the Jordan algebra of observables of a qutrit, we could say $\mathfrak{h}_3(\mathbb{O})$ is the Jordan algebra of observables of an 'octonionic qutrit'. In this language our result says roughly that the Standard Model gauge group is the group of symmetries of an octonionic qutrit that restrict to act as unitary operators on an ordinary qutrit and, within that, a qubit.