Infrared divergence in single-electron tunneling

In small-capacitance normal tunnel junctions, even a single-electron tunneling causes a substantial change in the localized Coulomb potential. If the perturbation may be regarded as static, Fermi liquid theory requires that infinitely many electron-hole pairs should be excited near the Fermi surface. It is shown that such infrared divergence leads to a power-law anomaly in tunneling conductance. Possible experimental situations to observe this effect are discussed.