The Spectrum of Darkonium in the Sun

TL;DR

This paper explores how dark matter captured in the Sun can form bound states and decay into dark photons, producing unique signals that help identify or constrain dark photon models.

Contribution

It introduces the concept of darkonium formation in the Sun and analyzes the resulting dark photon energy spectrum for detection prospects.

Findings

Dark matter can form bound states in the Sun, leading to distinctive decay signatures.

The energy spectrum of emitted dark photons is a mixture of various decay processes.

Potential signals outside the Sun can constrain dark photon models.

Abstract

Dark matter that gets captured in the Sun may form positronium-like bound states if it self-interacts via light dark photons. In this case, dark matter can either annihilate to dark photons or recombine in bound states which subsequently also decay to dark photons. The fraction of the dark photons that leave the Sun without decaying to Standard Model particles have a characteristic energy spectrum which is a mixture of the direct annihilation process, the decays of ortho- and para- bound states and the recombination process. The ultimate decay of these dark photons to positron-electron pairs (via kinetic mixing) outside the Sun creates a distinct signal that can either identify or set strict constraints on dark photon models.