Comment on ``Enhancement of the Tunneling Density of States in Tomonaga-Luttinger Liquids''

TL;DR

This paper critiques a recent calculation of the tunneling density of states in a Luttinger liquid, showing that the original result overestimated the DOS enhancement near an impurity.

Contribution

It identifies and corrects a subtle flaw in Oreg and Finkel'stein's calculation, demonstrating the DOS is suppressed rather than enhanced.

Findings

Original calculation overestimates DOS enhancement.

Corrected analysis shows DOS suppression at zero frequency.

Challenges previous claims of diverging DOS near impurities.

Abstract

In a recent Physical Review Letter, Oreg and Finkel'stein (OF) have calculated the electron density of states (DOS) for tunneling into a repulsive Luttinger liquid close to the location of an impurity. The result of their calculation is a DOS which is enhanced with respect to the pure system, and moreover diverging for not too strong repulsion. In this Comment we intend to show that OF's calculation suffers from a subtle flaw which, being corrected, results into a DOS not only vanishing at zero frequency but in fact suppressed in comparison with the DOS of a pure Luttinger liquid.