TUNNELING ZERO-BIAS ANOMALY IN THE QUASI-BALLISTIC REGIME

We study the tunneling density of states (DOS) of the interacting elec tron gas beyond the diffusive limit. A strong correction to the DOS pe rsists even at electron energies exceeding the inverse transport relax ation time. which could not be expected from the well-known Altshuler- Aronov-Lee (AAL) theory. This correction originates from the interfere nce between the electron waves scattered by an impurity and by the Fri edel oscillation this impurity creates. Account for such processes als o revises the AAL formula for the DOS in the diffusive limit.