Light from the Hidden Sector

TL;DR

This paper explores how optical experiments can detect hidden sector particles like paraphotons and minicharged particles, highlighting the role of magnetic fields and the potential to differentiate these from axion-like particles.

Contribution

It provides a detailed analysis of photon-paraphoton oscillations in optical experiments, emphasizing the sensitivity of upcoming light-shining-through-walls experiments to these hidden sector particles.

Findings

Upcoming experiments can detect paraphotons through photon oscillations.

Magnetic fields influence photon-paraphoton oscillation behavior.

Experiments can distinguish paraphotons from axion-like particles.

Abstract

Optical precision experiments are a powerful tool to explore hidden sectors of a variety of standard-model extensions with potentially tiny couplings to photons. An important example is given by extensions involving an extra light U(1) gauge degree of freedom, so-called paraphotons, with gauge-kinetic mixing with the normal photon. These models naturally give rise to minicharged particles which can be searched for with optical experiments. In this paper, we study the effects of paraphotons in such experiments. We describe in detail the role of a magnetic field for photon-paraphoton oscillations in models with low-mass minicharged particles. In particular, we find that the upcoming light-shining-through-walls experiments are sensitive to paraphotons and can distinguish them from axion-like particles.