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

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, Λη−2=(1.97±0.11tot)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 Λη−2 is lower than in previous results based on the η→e+e−γ decay. The value obtained for the ω slope parameter, Λωπ0−2=(1.99±0.21tot)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.