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arXiv · hep-ex/0206054

Search for an exotic three-body decay of orthopositronium

A. Badertscher·P. Crivelli·M. Felcini·S. N. Gninenko·N. A. Goloubev·P. Nedelec·J. P. Peigneux·V. Postoev·A. Rubbia·D. Sillou
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Abstract

We report on a direct search for a three-body decay of the orthopositronium into a photon and two penetrating particles, o-Ps -> gamma + X1 + X2. The existence of this decay could explain the discrepancy between the measured and the predicted values of the orthopositronium decay rate. From the analysis of the collected data a single candidate event is found, consistent with the expected background. This allows to set an upper limit on the branching ratio < 4.4 \times 10^{-5} (at the 90% confidence level), for the photon energy in the range from 40 keV < E_gamma< 400 keV and for mass values in the kinematical range 0 < mX1+mX2 <900 keV. This result unambiguously excludes the o-Ps -> gamma + X1 + X2 decay mode as the origin of the discrepancy.

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A. Badertscher, P. Crivelli, M. Felcini, S. N. Gninenko, N. A. Goloubev, P. Nedelec, J. P. Peigneux, V. Postoev, A. Rubbia, D. Sillou. 2002-06-21. Search for an exotic three-body decay of orthopositronium. https://doi.org/10.1016/s0370-2693(02)02237-2

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