Millicharge Dark Matter Detection with Mach-Zehnder Interferometer

TL;DR

This paper proposes using a Mach-Zehnder interferometer to detect earth-bound millicharge particles, potentially dark matter candidates, by measuring photon phase shifts, with sensitivity to certain parameters for particles over 1 GeV.

Contribution

It introduces a novel interferometric method to detect earth-bound millicharge particles, enhancing detection sensitivity for dark matter candidates.

Findings

Sensitivity to mixing parameter ε could reach 10^{-11} for mCPs over 1 GeV.

Detection is feasible if mCP number density exceeds 1 cm^{-3}.

Method provides a new approach to dark matter detection using laser interferometry.

Abstract

If the dark sector exists and communicates with Standard Model through the $U(1)$ mixing, it is possible that electromagnetism would have influence on matter fields in dark sector, so-called millicharge particles (mCPs). Furthermore, the highest mCPs could be dark matter particles. Recently it has been shown that the mCPs would be slowed down and captured by the earth. As a result, the number density of accumulated mCPs underground is enhanced by several orders of magnitude as compared to that of dark matter in our solar system. In this study, we propose to use the Mach-Zehnder (MZ) laser interferometer to detect earth bound mCPs through the detection of phase shifts of photons. We show that, for mass of mCPs lager than $1$ GeV, the sensitivity of probing the mixing parameter $\epsilon$ could reach as low as $10^{-11}$ if number density is larger than $1~\rm{cm^{-3}}$.