On stable lattices and the diagonal group

Abstract

Inspired by work of McMullen, we show that any orbit for the action of the diagonal group on the space of lattices, accumulates on a stable lattice. We use this to settle a conjecture of Ramharter about Mordell's constant, get new proofs of Minkowski's conjecture in dimensions up to seven, and answer a question of Harder on the volume of stable lattices.