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arXiv · hep-ex/9503004

A search for massive neutral bosons in orthopositronium decay

T. Maeno·M. Fujikawa·J. Kataoka·Y. Nishihara·S. Orito·K. Shigekuni·Y. Watanabe
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Abstract

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 ${\rm keV}/{\it c}^{2}$, 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 the upper-limits of\mbox{ }$2.0 \times 10^{-4}$ on the branching ratio of such a decay in the mass region from 847 to 1013 ${\rm keV}/{\it c}^{2}$, and excludes the possibility of this decay mode explaining the discrepancy in the orthopositronium decay-rate.

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T. Maeno, M. Fujikawa, J. Kataoka, Y. Nishihara, S. Orito, K. Shigekuni, Y. Watanabe. 1995-03-04. A search for massive neutral bosons in orthopositronium decay. https://doi.org/10.1016/0370-2693(95)00425-k

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