  In quantum wires, such as metallic nanotubes, the optical absorption of the
transverse polarization is controlled by the depolarization effect which stems
from the redistribution of conduction electrons around the circumference of the
system. The traditional electrostatics treatment of the depolarization effect
relies on approximating the system by a cylinder with some effective dielectric
permittivity. We demonstrate that this simple intuitive picture does not
adequately describe optical absorption near its threshold, as the
depolarization effect becomes dominated by many-body correlations which
strongly modify the spectral dependence of absorption.
