Measurement of the ω→π0e+e− and η→e+e−γ Dalitz decays with the A2 setup at the Mainz Microtron

Abstract

The Dalitz decays η→e⁺e^−γ and ω→π⁰e⁺e^− have been measured in the γp→ηp and γp→ωp reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron. The value obtained for the slope parameter of the electromagnetic transition form factor of η, Λ^−2_η=(1.97±0.11_tot)GeV^−2, is in good agreement with previous measurements of the η→e⁺e^−γ and η→μ⁺μ^−γ decays. The uncertainty obtained in the value of Λ^−2_η is lower than in previous results based on the η→e⁺e^−γ decay. The value obtained for the ω slope parameter, Λ^−2_{ωπ⁰}=(1.99±0.21_tot)GeV^−2, is somewhat lower than previous measurements based on ω→π⁰μ⁺μ^−, but the results for the ω transition form factor are in better agreement with theoretical calculations, compared to earlier experiments.