Response functions of two-coupled chains of Tomonaga-Luttinger liquids

Abstract Properties of fluctuations in two chains of Tomonaga–Luttinger liquids coupled by the interchain hopping have been studied by calculating retarded response functions χ ρ R ( q x , q y ; ω ) for charge and χ σ R ( q x , q y ; ω ) for spin where q x and q y (=0 or π ) denote the longitudinal and transverse wave vector, respectively, and ω is the frequency. We have found the notable fact that the repulsive intrachain interaction results in the clear enhancement of Im χ σ R ( q x , π ; ω ) and the suppression of Im χ ρ R ( q x , π ; ω ) at low energies. This result indicates the importance of the dynamical effect by the spin fluctuation with q y = π and small ω , which has a possibility to give rise to the attractive interaction for the electron pairing.