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New particles |
A new light vector X-boson with an interactive Lagrangian
will also result in an invisible decay of o-Ps. The interest for this kind of particles was raised by the BNL measurements on the g-2 for the muon. Supposing that this boson interact with fermions it will contribute to the anomalous magnetic moment for the electron, giving a bound for the coupling constant of
where ax=gx2/4p. For the reaction
where X* is the virtual X boson and X1 is a fermion (sterile neutrino) or scalar particle, the branching ratio is given by
A search for this light boson with me << mx and a coupling constant axx1=gxx12/4p<10-5 requires to be comparable with the Brookheaven experiment a sensitivity,
OBr(o-Ps &rarr invisible) < 10-8
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