Analysis of semileptonic decay widths of η(1295,1475) mesons

Abstract

The decays of excited and mesons with the production of vector mesons  and a lepton pair  and are investigated. It is shown that these decays are described by a contact diagram with direct production of a lepton pair by a photon field and a diagram with intermediate vector fields  and . Theoretical estimates for the integral decay widths are obtained.The relative roles of the channels in determining the decay widths are investigated. It is shown that decays with the production of an electron-positron pair are mainly determined by the contribution of the diagram with contact interaction. Channels with vector mesons play a more important role in the decays of mesons  with the production of a muon pair.The matrix elements corresponding to the quark loops with vertices  and  are calculated. Mesons  and  are considered as the first radially excited states of mesons  and .The calculations are performed in the one-loop quark approximation in the leading order of the 1/Nс expansion. Predictions for a number of processes planned in future hadron factories are obtained. The results of theoretical calculations are important for understanding the structure of mesons and their interaction with hadron and lepton fields. The obtained decay data can be used in future meson factories.The implementation of such a hadron factory is planned at the Fermilab proton beam where the number of events is expected to be at the level of  for the  – meson which is several orders of magnitude higher than current experiments. Another meson factory will be built at the HIAF heavy ion accelerator in China.