Constraints on hidden photons from current and future observations of CMB spectral distortions

TL;DR

This paper updates constraints on hidden photon properties using current and future CMB spectral distortion measurements, significantly tightening bounds on their kinetic mixing and mass.

Contribution

It provides new, more stringent bounds on hidden photon parameters based on recent and forecasted CMB spectral distortion data.

Findings

Kinetic mixing angle $ ext{χ}_0$ must be less than $10^{-8}$ for certain masses.

Bounds are over ten times stronger than previous COBE/FIRAS limits.

Future experiments like PIXIE and PRISM/COrE will further improve constraints.

Abstract

A variety of beyond the standard model scenarios contain very light hidden sector U(1) gauge bosons undergoing kinetic mixing with the photon. The resulting oscillation between ordinary and hidden photons leads to spectral distortions of the cosmic microwave background. We update the bounds on the mixing parameter $\chi_0$ and the mass of the hidden photon $m_{\gamma'}$ for future experiments measuring CMB spectral distortions, such as PIXIE and PRISM/COrE. For $10^{-14}\;{\rm eV}\lesssim m_{\gamma'}\lesssim 10^{-13}\;{\rm eV}$, we find the kinetic mixing angle $\chi_0$ has to be less than $10^{-8}$ at 95\% CL. These bounds are more than an order of magnitude stronger than those derived from the COBE/FIRAS data.