Study of the $\rho$ and $\omega$ meson decays into pseudoscalar meson and $e^+e^-$ pair with the CMD-2 detector

TL;DR

This study measures the decay rates of $ ho$ and $\omega$ mesons into pseudoscalar mesons and electron-positron pairs using CMD-2 data, providing precise branching fractions and upper limits for rare decay modes.

Contribution

First measurement of the $ ext{ extomega} o ext{ extpi}^0 e^+ e^-$ decay branching fraction with improved precision and new upper limits for other rare meson decay modes.

Findings

Measured $ ext{ extomega} o ext{ extpi}^0 e^+ e^-$ branching fraction: (8.19±0.71±0.62)×10⁻⁴

Set upper limits for $ ho o ext{ extpi}^0 e^+ e^-$, $ ho o ext{ exteta} e^+ e^-$, and $ ext{ extomega} o ext{ exteta} e^+ e^-$ decays

Data collected with CMD-2 in the 720–840 MeV energy range

Abstract

Using 3.3 pb$^{-1}$ of data collected with the CMD-2 detector in the 720 -- 840 MeV c.m. energy range, the branching fraction of the conversion decay $\omega\to\pi^0e^+e^-$ has been measured: $\mathcal{B}(\omega\to\pi^0e^+e^-)=(8.19\pm0.71\pm0.62)\cdot10^{-4}$. The upper limits for the branching fractions of the following conversion decays have been obtained at the 90% confidence level: $\mathcal{B}(\rho\to\pi^0e^+e^-)<1.6\cdot10^{-5}$, $\mathcal{B}(\rho\to\eta e^+e^-)<0.7\cdot10^{-5}$ and $\mathcal{B}(\omega\to\eta e^+e^-)<1.1\cdot10^{-5}$.