Enhancement of the tunneling density of states in Tomonaga--Luttinger   Liquids
  We have calculated the tunneling density of states (DOS) at the location of a backward scattering defect for quantum wires and for edge state electrons in quantum Hall systems. A singular enhancement of the DOS arises as a result of the combined effect of multiple backward scattering together with a repulsive electron---electron interaction. 
Yuval Oreg and Alexander M. Finkel'stein