  I study the zero temperature phase transition between superfluid and
insulating ground states of the Bose-Hubbard model in a random chemical
potential and at large integer average number of particles per site. Duality
transformation maps the pure Bose-Hubbard model onto the sine-Gordon theory in
one dimension (1D), and onto the three dimensional Higgs electrodynamics in two
dimensions (2D). In 1D the random chemical potential in dual theory couples to
the space derivative of the dual field, and appears as a random magnetic field
along the imaginary time direction in 2D. I show that the transition from the
superfluid state in both 1D and 2D is always controlled by the random critical
point. This arises due to a coupling constant in the dual theory with replicas
which becomes generated at large distances by the random chemical potential,
and represents a relevant perturbation at the pure superfluid-Mott insulator
fixed point. At large distances the dual theory in 1D becomes equivalent to the
Haldane's macroscopic representation of disordered quantum fluid, where the
generated term is identified with random backscattering. In 2D the generated
coupling corresponds to the random mass of the complex field which represents
vortex loops. I calculate the critical exponents at the superfluid-Bose glass
fixed point in 2D to be \nu=1.38 and z=1.93, and the universal conductivity at
the transition \sigma_c = 0.26 e_{*}^2 /h, using the one-loop field-theoretic
renormalization group in fixed dimension.
