  We derive a continuum theory for the phase transition in a classical dimer
model on the cubic lattice, observed in recent Monte Carlo simulations. Our
derivation relies on the mapping from a three-dimensional classical problem to
a two-dimensional quantum problem, by which the dimer model is related to a
model of hard-core bosons on the kagome lattice. The dimer-ordering transition
becomes a superfluid-Mott insulator quantum phase transition at fractional
filling, described by an SU(2)-invariant continuum theory.
