Superfluid-insulator transition in a disordered two-dimensional quantum rotor model with random on-site interactions

We study the superfluid-insulator quantum phase transition in a disordered two-dimensional quantum rotor model with random on-site interactions in the presence of particle-hole symmetry. Via worm-algorithm Monte Carlo calculations of superfluid density and compressibility, we find the dynamical critical exponent $z\approx 1.13(2)$ and the correlation length critical exponent $1/\nu \approx 1.1(1)$. These exponents suggest that the insulating phase is a incompressible Mott glass rather than a Bose glass.