Nonlinear sigma model with particle-hole asymmetry for the disordered two-dimensional electron gas

 

The nonlinear sigma model is a well-established theoretical tool for studies of transport and thermodynamics in disordered electronic systems. An important application is the description of the metallic side of the metal-insulator transition in the two-dimensional electron gas. The conventional sigma model approach for interacting systems does not account for particle-hole asymmetry. It is therefore not suited for studying quantities that are sensitive to this effect such as the thermoelectric transport coefficient. We derive a minimal extension of the Keldysh nonlinear sigma model tailored for two-dimensional interacting systems. We argue that this model can be used to systematically study the combined effect of interactions and disorder on thermoelectric transport. We use the model to analyze the structure of the heat density-density correlation function and calculate interaction corrections to its static part.