# Photon polarizability and its effect on the dispersion of plasma waves

## TL;DR

This paper investigates how high-frequency photon polarizability affects plasma wave dispersion, providing two formulations—one via ponderomotive forces and another through photon polarizability—for a comprehensive understanding.

## Contribution

It introduces a novel analysis of photon polarizability's impact on plasma wave dispersion, offering two distinct theoretical approaches for the first time.

## Key findings

- Photon polarizability influences plasma wave dispersion.
- Two formulations provide consistent results for Langmuir wave modification.
- The photon contribution can be incorporated without ponderomotive force calculations.

## Abstract

High-frequency photons traveling in plasma exhibit a linear polarizability that can influence the dispersion of linear plasma waves. We present a detailed calculation of this effect for Langmuir waves as a characteristic example. Two alternative formulations are given. In the first formulation, we calculate the modified dispersion of Langmuir waves by solving the governing equations for the electron fluid, where the photon contribution enters as a ponderomotive force. In the second formulation, we provide a derivation based on the photon polarizability. Then, the calculation of ponderomotive forces is not needed, and the result is more general.