Ultranarrow resonance in Coulomb drag between quantum wires at coinciding densities

We investigate the influence of the chemical potential mismatch $\mathrm{\Delta }$ (different electron densities) on Coulomb drag between two parallel ballistic quantum wires. For pair collisions, the drag resistivity ${\rho }_{\mathrm{D}}(\mathrm{\Delta })$ shows a peculiar anomaly at $\mathrm{\Delta }=0$ with ${\rho }_{\mathrm{D}}$ being finite at $\mathrm{\Delta }=0$ and vanishing at any nonzero $\mathrm{\Delta }$. The “bodyless” resonance in ${\rho }_{\mathrm{D}}(\mathrm{\Delta })$ at zero $\mathrm{\Delta }$ is only broadened by processes of multi-particle scattering. We analyze Coulomb drag for finite $\mathrm{\Delta }$ in the presence of both two- and three-particle scattering within the kinetic equation framework, focusing on a Fokker-Planck picture of the interaction-induced diffusion in momentum space of the double-wire system. We describe the dependence of ${\rho }_{\mathrm{D}}$ on $\mathrm{\Delta }$ for both weak and strong intrawire equilibration due to three-particle scattering.