SEMICLASSICAL THEORY OF THE COULOMB ANOMALY

An effective action approach for the problem of Coulomb blocking of tu nneling is discussed. The method is applied to the strong-coupling pro blem arising near zero bias, where perturbation theory diverges. We fi nd an instanton for the electrodynamics in imaginary time, and express the anomaly in terms of the exact conductivity of the system sigma(om ega,q) and the exact interaction. (C) 1997 American Institute of Physi cs.