Search for short-lived neutral bosons in orthopositronium decay

S. Asai, K. Shigekuni, T. Sanuki, S. Orito

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


We searched for an exotic decay of orthopositronium into a single photon and a short-lived neutral boson ø0 in hitherto unexplored mass region below 300 keV/c2. A high-resolution measurement of the associated photon energy spectrum was carried out with a germanium detector to discriminate the expected sharp peak of this decay from the broader peak of the pick-off annihilations. No evidence of such decay was observed, resulting in the upper-limits on the branching ratio of 3.0×10-4 (mΦ0<500 keV/c2). This clearly rules out the possibility of this exotic decay mode explaining the reported discrepancy in the orthopositronium decay rate.

Original languageEnglish
Pages (from-to)90-94
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1
Publication statusPublished - 1994 Mar 3


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