QED Second Order Corrections on the Speed of Light at Low Temperature

TL;DR

This paper investigates how low-temperature thermal effects in quantum electrodynamics (QED) cause second-order corrections to the speed of light, revealing dispersive medium behavior and comparing with existing models.

Contribution

It introduces a two-loop level calculation of photon vacuum polarization in QED to analyze thermal corrections to light speed at low temperatures.

Findings

Speed of light decreases proportionally to the second order of temperature.

Thermal corrections behave as a dispersive medium affecting light propagation.

Comparison with Euler-Heisenberg and electromagnetic medium models shows similarities and differences.

Abstract

We want to study thermal corrections on the speed of light at low temperature considering temperature dependence of photon vacuum polarization tensor at two-loop level in the standard QED. It is found that the heat bath behaves as a dispersive medium to the propagation of light and reduces its speed proprtional to the second order of temperature. Similiraties and differences with already known calculations which are based on Euler-Heisenberg Lagrangian and/or those using temperature dependent electromagnetic properties of the medium are discussed.