Photonic dark matter portal revisited

TL;DR

This paper investigates the effects of a hidden photonic portal on exotic atoms, tightens bounds on coupling constants, and explores potential explanations for observed X-ray signals related to dark matter decay.

Contribution

It extends previous work by analyzing muonium and positronium, providing tighter coupling bounds, and connecting dark matter decay to observed X-ray lines.

Findings

Tighter upper limit on hidden photonic portal coupling.

Negligible Aharonov-Bohm phase shift due to dark matter.

Calculated coupling constant consistent with 3.5 keV X-ray line.

Abstract

In our previous paper [1], we studied a model of dark matter (DM) in which the hidden sector interacts with standard model particles via a hidden photonic portal (HP). We investigated the effects of this new interaction on the hydrogen atom and obtained an upper bound for the coupling of the model. In this work, we study the effects of HP on two interesting exotic atoms namely muonium and positronium. We obtain a tighter upper limit on the coupling. We also calculate the change (shift) in the Aharonov-Bohm phase due to HP and find that the phase shift is negligibly small (for DM particles mass in the GeV range). Recently a 3.5 keV X ray line signal observed in the spectrum of 73 galaxy clusters, reported by the XXM-Newton X ray observatory. Since in HP model the DM particles can decay directly into photons, so we finally calculate the value of the coupling constant f using the condition Delta E=3.5 keV.