Thermal photon dispersion law and modified black-body spectra

TL;DR

This paper investigates the dispersion law of thermal photons under an SU(2) gauge principle, revealing temperature-dependent modifications to black-body spectra and confirming earlier findings on CMB correlations.

Contribution

It provides a numerical computation of the photon dispersion relation beyond the $p^2=0$ approximation, showing a faster gap shrinking in black-body spectra at higher temperatures.

Findings

Exact dispersion exhibits a power-like gap shrinking with temperature.

Approximate $p^2=0$ results are valid for temperatures up to twice the CMB temperature.

Large-angle CMB correlations remain consistent with previous approximations.

Abstract

Based on the postulate that photon propagation is governed by an SU(2) gauge principle we numerically compute the one-loop dispersion for thermalized photon propagation on the radiatively induced mass shell. Formerly, the dispersion was addressed by assuming $p^2=0$. While this approximation turns out to be excellent for temperatures $\le 2 T_{\tiny{CMB}}$ the exact result exhibits a much faster (power-like) shrinking of the gap in the black-body spectral intensity with rising temperature. Our previous statements on anomalous large-angle CMB temperature-temperature correlations, obtained in the approximation $p^2=0$, remain valid.