We show that electron--electron scattering gives a positive contribution to the resistivity of ballistic multimode wires whose width is much smaller than their length. This contribution is not exponentially small at low temperatures and therefore may be experimentally observable. It scales with temperature as T2 for three-dimensional channels and as T5/2 for two-dimensional ones.
@article{arxiv.1110.2607,
title = {Electron-Electron scattering and resistivity of ballistic multimode channels},
author = {K. E. Nagaev and N. Yu. Sergeeva},
journal= {arXiv preprint arXiv:1110.2607},
year = {2012}
}