A search for massive neutral bosons in orthopositronium decay

T. Maeno*, M. Fujikawa, J. Kataoka, Y. Nishihara, S. Orito, K. Shigekuni, Y. Watanabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


We have searched for an exotic decay of orthopositronium into a single photon and a short-lived neutral boson in the hitherto unexplored mass region above 900 keV/c2, by noting that this decay is one of few remaining candidates which could explain the discrepancy of the orthopositronium decay rate. A high-resolution measurement of the associated photon energy spectrum was carried out with a germanium detector to search for a sharp peak from this two-body decay. Our negative result provides an upper limit of 2.0 × 10-4 on the branching ratio of such a decay in the mass region from 847 to 1013 keV/c2, and excludes the possibility of this decay mode explaining the discrepancy in the orthopositronium decay rate.

Original languageEnglish
Pages (from-to)574-578
Number of pages5
JournalPhysics Letters B
Issue number4
Publication statusPublished - 1995 Jun 1
Externally publishedYes


  • Decay rate
  • Exotic decay
  • Germanium detector
  • Neutral boson
  • Orthopositronium decay
  • QED

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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