Can the mirror world explain the ortho - positronium lifetime puzzle ?

We suggest that the discrepant lifetime measurements of ortho-positronium can be explained by ortho-positronium oscillations into mirror ortho-positronium. This explanation can be tested in future vacuum experiments. [email protected] [email protected] A “mirror universe” is predicted to exist if parity and/or time reversal are unbroken symmetries of nature [1,2]. The idea is that for each ordinary particle, such as the photon, electron, proton and neutron, there is a corresponding mirror particle, of exactly the same mass as the ordinary particle. The parity symmetry interchanges the ordinary particles with the mirror particles so that the properties of the mirror particles completely mirror those of the ordinary particles. For example the mirror proton and mirror electron are stable and interact with the mirror photon in the same way in which the ordinary proton and electron interacts with the ordinary photons. The mirror particles are not produced in Laboratory experiments just because they couple very weakly to the ordinary particles. In the modern language of gauge theories, the mirror particles are all singlets under the standard G ≡ SU(3) ⊗ SU(2)L ⊗ U(1)Y gauge interactions. Instead the mirror particles interact with a set of mirror gauge particles, so that the gauge symmetry of the theory is doubled, i.e. G ⊗ G (the ordinary particles are, of course, singlets under the mirror gauge symmetry) [2]. Parity is conserved because the mirror particles experience V +A (i.e. righthanded) mirror weak interactions while the ordinary particles experience the usual V − A (i.e. left-handed) weak interactions. Ordinary and mirror particles interact with each other predominately by gravity only. At the present time there is some experimental evidence that mirror matter exists coming from cosmology [3] as well as from the neutrino physics anomalies [4]. It was realized some time ago by Glashow [5] that the orthopositronium system provides one sensitive way to search for the mirror universe. The idea is that small kinetic mixing of the ordinary and mirror photons may exist which would mix ordinary and mirror orthopositronium, leading to maximal orthopositronium mirror orthopositronium oscillations. The ground state of orthopositronium (o-Ps) decays predominately into 3 photons with a theoretical decay rate computed to be (see e.g. [6] for a review)