Tests of the fundamental symmetries in η meson decays
2011 (English)In: Journal of Physics: Conference Series, Vol. 335Article in journal (Refereed) Published
Patterns of chiral symmetry violation and tests of the conservation of the fundamental C , P and CP symmetries are key physics issues in studies of the Ï€ 0 , Î· and Î·’ meson decays. These tests include searches for rare or forbidden decays and searches for asymmetries among the decay products in the not-so-rare decays. Some examples for the rare decays are Î· â†’ 2 Ï€ , Î· â†’ 4 Ï€ 0 ( CP tests), decays into an odd number of photons ( e.g. , Î· â†’ 3 Î³ ) and the decay Î· â†’ Ï€ 0 e + e âˆ’ ( C tests). In the conversion decay Î· â†’ Ï€ + Ï€ âˆ’ e + e âˆ’ , the asymmetry in the distribution of the angle between the two-pion and two-lepton decay planes allows to search for CP violation in a flavor-conserving process beyond the CKM mechanism which is not constrained by the limits on the neutron dipole moment. In addition, the Dalitz decays and the decays into a lepton-antilepton pair are sensitive to contributions from a vector boson responsible for the annihilation of hypothetical light dark matter particles. The muon g â€“ 2 and the branching ratio for the Ï€ 0 e + e âˆ’ decay are currently the observables where hints of a deviation from the Standard Model predictions are reported. The experimental studies of the Ï€ 0 , Î· and Î·’ meson decays are carried out at four European accelerator research facilities: KLOE/KLOE-2 at DAFNE (Frascati), Crystal Ball at MAMI (Mainz), WASA at COSY (JÃŒlich), Crystal Barrel at ELSA (Bonn).
Place, publisher, year, edition, pages
2011. Vol. 335
IdentifiersURN: urn:nbn:se:uu:diva-170099OAI: oai:DiVA.org:uu-170099DiVA: diva2:508281