One-Particle vs. Two-Particle Crossover in Weakly Coupled Hubbard Chains and Ladders: Perturbative Renormalization Group Approach

Physical nature of dimensional crossovers in coupled one-dimensional systems has currently provoked a great deal of controversy. Recent discovery of the superconductivity in the doped spin ladder under pressure has stimulated us to study the dimensional crossover problem in the weakly coupled ladder system. In the present work, based on the perturbative renormarization-group approach (PRG) developed by Bourbonnais and Caron, we discuss the dimensional crossovers induced by the inter-chain/ladder one-particle hopping, t⊥, in the weakly coupled chains or ladders, with emphasis on the differences between these systems.