Theory of a pair density wave on a quasi-one-dimensional lattice in the Hubbard model

In this study, we examine the superconducting instability of a quasi-one-dimensional lattice in Hubbard model based on random-phase approximation (RPA) and fluctuation exchange (FLEX) approximation. We find that spin-singlet pair density wave (PDW-singlet) with center-of-mass momentum $2k_F$ can be stabilized when one-dimensionality becomes prominent toward perfect nesting Fermi surface. The obtained is mixture even-frequency odd-frequency singlet ones. dominant component does not have nodal lines This PDW-singlet state more favorable as compared to RPA self-energy correction introduced FLEX