Study of conversion decays phi->etae+e-, eta->e+e-g and eta->pi+pi-e+e- at CMD-2

TL;DR

This study measures branching ratios of specific meson conversion decays using CMD-2 data, providing new experimental results and upper limits for rare decay processes in the phi and eta mesons.

Contribution

It presents the first precise measurements of certain phi and eta meson conversion decay branching ratios and sets upper limits on rare decay modes.

Findings

Measured branching ratios for phi->eta e+e- and eta decays.

Set upper limits for rare phi and eta decay modes.

Provided experimental data at the phi-meson energy range.

Abstract

Using 15.1 pb^{-1} of data collected by CMD-2 in the phi-meson energy range, the branching ratios of the following conversion decays have been measured: B(\phi\to\eta e^+e^-) = (1.14\pm0.10\pm0.06)\cdot10^{-4}, B(\eta\to e^+e^-\gamma) = (7.10\pm0.64\pm0.46)\cdot10^{-3}, B(\eta\to\pi^+\pi^-e^+e^-) = (3.7^{+2.5}_{-1.8}\pm0.3)\cdot10^{-4}. The upper limits for the following rare conversion decays have been obtained at the 90% confidence level: B(\phi\to\eta\mu^+\mu^-) < 9.4\cdot10^{-6}, B(\eta\to e^+e^-e^+e^-) < 6.9\cdot10^{-5}.