  The Fermi edge singularity (FES) is a prominent manifestation of the Coulomb
interaction. It can be observed in a controllable way by studying the transport
through a quantum dot (QD), which is electrostatically coupled to the leads. In
this paper we study how FES affects higher order tunneling processes
(cotunneling). To address this problem we use the bosonic description of the
electrons in the leads, which naturally accounts for the Coulomb interaction.
We report the multiscale dependence of the current through the QD on the energy
of the QD level and on the bias between the leads obtained for the limit of
large and small bias. The new universal powers are determined by the scattering
phases due to the interaction of electrons in the leads with the charge on the
QD.

Mesoscale and Nanoscale Physics