An Improved Limit on Invisible Decays of Positronium

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dc.creatorBadertscher, A.
dc.creatorCrivelli, P.
dc.creatorFetscher, W.
dc.creatorGendotti, U.
dc.creatorGninenko, S.
dc.creatorPostoev, V.
dc.creatorRubbia, A.
dc.creatorSamoylenko, V.
dc.creatorSillou, D.
dc.date2006-09-29
dc.date2006-10-05
dc.date.accessioned2026-07-07T10:24:41Z
dc.date.available2026-07-07T10:24:41Z
dc.descriptionThe results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evid ence for new physics beyond the Standard Model (SM): for example the existence of extra--dimensions, of milli-charged particles, of new light gauge bosons or of mirror particles. Mirror matter could be a relevant dark matter candidate. In this paper the setup and the results of a new experiment are presented. In a collected sample of about $(6.31\pm0.28) \times 10^6$ orthopositronium decay s, no evidence for invisible decays in an energy window [0,80] keV was found and an upper limit on the branching ratio of orthopositronium \invdecay could be set: $\binvdecay<4.2\times 10^{-7}$ (90% C.L.) Our results provide a limit on the photon mirror-photon mixing strength $ε\leq 1.55\times 10^{-7}$ (90% C.L.) and rule out particles lighter than the electron mass with a fraction $Q_x \leq 3.4 \times 10^{-5}$ of the electron charge. Furthermore, upper limits on the branching ratios for the decay of parapositronium $Br(p-Ps\to invisible)\leq 4.3 \times 10^{-7}$ (90% C.L.) and the direct annihilation $Br(e^+e^-\to invisible)\leq 2.1 \times 10^{-8}$ (90% C.L.) could be set.
dc.description17 pages, 7 figures, added references, fixed limit on millicharged particles and changed two plots accordingly
dc.identifierhttps://arxiv.org/abs/hep-ex/0609059
dc.identifierhttp://arxiv.org/abs/hep-ex/0609059
dc.identifierPhys.Rev.D75:032004,2007
dc.identifierdoi:10.1103/PhysRevD.75.032004
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/176277
dc.subjectHigh Energy Physics - Experiment
dc.titleAn Improved Limit on Invisible Decays of Positronium
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