  We study the transition between a Coulomb phase and a dimer crystal observed
in numerical simulations of the three-dimensional classical dimer model, by
mapping it to a quantum model of bosons in two dimensions. The quantum phase
transition that results, from a superfluid to a Mott insulator at fractional
filling, belongs to a class that cannot be described within the
Landau-Ginzburg-Wilson paradigm. Using a second mapping, to a dual model of
vortices, we show that the long-wavelength physics near the transition is
described by a U(1) gauge theory with SU(2) matter fields.
