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Positronium as a probe of new physics |
Motivations for the invisible decay search of orthopositronium
The Standard Model of particle physics predicts invisible decay of orthopositronium in a neutrino-antineutrino pair, the calculated branching ratio for this process is less than 10-19. Since this decay rate is very small, an evidence for invisible decays would unambiguously signal the presence of new physics.
The new models that are relevant to the o-Ps &rarr invisible decay mode predict the existence either of
i) extra-dimensions
ii) fractionally charged particles
iii) new
particles
iv) dark matter of the mirror matter type
The required sensitivity in the branching ratio Br(o-Ps &rarr invisible) for the possible observation of these phenomena has to be at least as low as 10-8.
Invisible decays search of orthopositronium
To test the first three motivations the experiment does not need to be performed in vacuum, for the search of dark mirror matter the vacuum is essential, as it will be explained later.
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Some photos from the experiments |
15-05-2003 Status of the calorimeter 15-11-2002 Status of the beam 25-02-2002 First set-up for positronium measurements 31-01-2002 Tests of BGO crystals for the calorimeter |
Last update: P. Crivelli - November 13 2004