Searching for light dark matter through Positronium decay

Abstract: A novel approach to detect light dark matter through the observation of a single photon in the decay of Positronium (Ps) is proposed. Branching ratio calculations indicate that light dark matter coupling to the Standard Model through a novel dark vector boson in the mass range m_A′ = 10–500 keV with strength ϵ = 2 × 10⁻⁵–10⁻⁸ is well above the previously computed Standard Model background decay Ps → and could be sensitive to observation. Graphical abstract: [Figure not available: see fulltext.].