Limit on an exotic three-body decay of orthopositronium
Department of Physics, Faculty of Science, University of Tokyo, Tokyo 113, Japan
Accepted: 27 November 1995
An exotic annihilation of at rest into a single γ and a weakly interacting neutral vector boson was searched for by measuring the related γ energy under the condition that no additional γ was detected by a hermetic detector. No evidence of such an annihilation was observed, resulting in the upper limits on the branching ratio of ( keV/c2) and ( keV/c2). These upper limits were converted to those on the branching ratio of an exotic three-body decay () of orthopositronium (o-Ps), i.e. ( keV/c2) and (). As a result, this mode was definitely excluded as the source of the reported discrepancy in the o-Ps decay rate.
PACS: 14.80.-j – Properties of specific particles: Other particles (including hypothetical) / 36.10.Dr – Positronium, muonium, muonic atoms and molecules / 12.20.Fv – Experimental tests
© EDP Sciences, 1996