Tunneling spectroscopy of Luttinger-liquid structures far from equilibrium

We develop a theory of tunneling spectroscopy of interacting electrons in a nonequilibrium quantum wire coupled to reservoirs. The problem is modeled as an out-of-equilibrium Luttinger liquid with spatially dependent interaction. The interaction leads to the renormalization of the tunneling density of states, as well as to the redistribution of electrons over energies. Energy relaxation is controlled by plasmon scattering at the boundaries between regions with different interaction strengths and affects the distribution function of electrons in the wire as well as that of electrons emitted from the interacting regions into noninteracting electrodes.