Generic incommensurate transition in the two-dimensional boson Hubbard model

The generic transition in the boson Hubbard model, occurring at an incommensurate chemical potential, is studied in the link-current representation using the recently developed directed geometrical worm algorithm. We find clear evidence for a multipeak structure in the energy distribution for finite lattices, usually indicative of a first-order phase transition. However, this multipeak structure is shown to disappear in the thermodynamic limit, …