2003/11/30 by Aneesh V. Manohar, Pedro Ruiz-Femenía, Pedro Ruiz-Femenia
Physics and Astronomy · #Atomic and Subatomic Physics Research #Neutrino Physics Research #Radiation Detection and Scintillator Technologies #hep-ph #physics.atom-ph
paper · pdf · doi:10.1103/physrevd.69.053003
published as Phys.Rev. D69 (2004) 053003 · added computation of decay spectrum using 4-fermion local annihilation operators
arxiv created 2004/01/09 · openalex publication_date 2004/03/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The photon spectrum in orthopositronium \ensuremath→3\ensuremathγ decay is computed using effective field theory methods. For energetic photons, the spectrum agrees with the Ore-Powell result, but deviates from it when the photon energy is comparable to the positronium binding energy. The decay spectrum in this region depends on a positronium structure function, which is computed in this paper. At still lower energies the photon spectrum is dominated by the parapositronium resonance contribution. Our results are compatible with Low's theorem on soft photon emission.