  Motivated by the intersection theory of moduli spaces of curves, we introduce
psi classes in matroid Chow rings and prove a number of properties that
naturally generalize properties of psi classes in Chow rings of Losev-Manin
spaces. We then use these properties of matroid psi classes to give new proofs
of known formulas for the volume polynomials of matroids, which were previously
proved by Eur and by Backman, Eur, and Simpson.
