Study of resonant inelastic light scattering in Keldysh-Schwinger functional integral formalism

TL;DR

This paper develops a Keldysh-Schwinger functional integral method to compute resonant inelastic light scattering cross sections, including many-body effects, and applies it to graphene's G-phonon Raman scattering, extending to non-equilibrium systems.

Contribution

It introduces a novel functional integral formalism for resonant inelastic light scattering, allowing full many-body effect incorporation and generalization to non-equilibrium conditions.

Findings

Method agrees with conventional Fermi golden rule results for graphene.

Enables computation of scattering in non-equilibrium systems.

Provides a unified framework for many-body light scattering analysis.

Abstract

The scattering cross section of the resonant inelastic light scattering is represented as a correlation function in the Keldysh-Schwinger functional integral formalism. The functional integral approach enables us to compute the cross section in the Feynman diagram perturbation theory where many-body effects can be fully incorporated. This approach is applied to the one G-phonon Raman scattering of graphene, and the result is shown to agree with the one previously obtained by the conventional Fermi golden rule formula. Also, this approach is generalized to the systems in non-equilibrium conditions.