Dark photon limits from patchy dark screening of the cosmic microwave background

TL;DR

This paper sets the strongest constraints to date on dark photon kinetic mixing by analyzing spectral anisotropies in the CMB caused by photon-dark photon conversion within large-scale structures, using Planck and galaxy survey data.

Contribution

It provides the tightest limits on dark photon kinetic mixing over a specific mass range using advanced component separation and cross-correlation techniques.

Findings

Constraints on kinetic mixing parameter $ ext{ε} \, \lesssim 4\times 10^{-8}$ (95% CL)

Mass range constrained: $10^{-13}$ to $10^{-11}$ eV

Almost an order of magnitude improvement over previous limits

Abstract

Dark photons that kinetically mix with the Standard Model photon give rise to new spectral anisotropies (patchy dark screening) in the cosmic microwave background (CMB) due to conversion of photons to dark photons within large-scale structure. We utilize predictions for this patchy dark screening signal to provide the tightest constraints to date on the dark photon kinetic mixing parameter ($\varepsilon \lesssim 4\times 10^{-8}$ (95% confidence level)) over the mass range $10^{-13} \,\, {\rm eV} \lesssim m_{{A^\prime}} \lesssim 10^{-11}$ eV, almost an order of magnitude stronger than previous limits, by applying state-of-the-art component separation techniques to the cross-correlation of $\textit{Planck}$ CMB and $\textit{unWISE}$ galaxy survey data.