One-dimensional repulsive Hubbard model with mass imbalance: orders and filling-anomaly

We investigate the phase diagram of the one-dimensional repulsive Hubbard model with mass imbalance. Using DMRG, we show that this model has a triplet paired phase (dubbed $pi SG$) at generic fillings, consistent with previous theoretical analysis. We study the topological aspect of $pi SG$ phase, determining long-range string orders and the filling anomaly which refers to the relation among single particle gap, inversion symmetry and filling imbalance for open chains. We also find, using DMRG, that at $1/3$ filling, commensurate effects lead to two additional phases: a crystal phase and a trion phase; we construct a description of these phases using Tomonaga-Luttinger liquid theory.