Experimental study of the e^+e^-\to\pi^+\pi^-\pi^0 reaction by SND detector in the energy range sqrt{s}=0.42--1.38 GeV

TL;DR

This study analyzes the e^+e^- o ext{pi}^+ ext{pi}^- ext{pi}^0 reaction using SND detector data in the 0.42 to 1.38 GeV energy range, revealing resonance parameters and reaction dynamics, including evidence of suppressed rho to 3pi decay.

Contribution

First detailed measurement of the e^+e^- o ext{pi}^+ ext{pi}^- ext{pi}^0 process across a broad energy range, highlighting the role of intermediate states and decay suppression effects.

Findings

Resonance parameters of ho, \, ext{omega}, \, ext{phi} obtained.

Reaction dynamics dominated by ho ext{pi} and ext{omega} ext{pi}^0 intermediate states.

Evidence of suppressed ho o 3 ext{pi} decay with a branching ratio of about 10^{-4}.

Abstract

The review of the SND results of the $e^+e^-\to\pi^+\pi^-\pi^0$ process study in the energy range $\sqrt[]{s}=0.42$ -- 1.38 GeV at VEPP-2M collider, based on about $2\times 10^6$ selected events, is presented. The total cross section, parameters of the $\rho$, $\omega$, $\phi$ resonances, and $\omega^\prime$, $\omega^{\prime\prime}$ states were obtained. It was found that $\rho\pi$ and $\omega\pi^0$ intermediate states describe the reaction dynamics. The experimental data cannot be described by a sum of only $\omega$, $\phi$, $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions. This can be interpreted as a manifestation of the $\rho\to 3\pi$ decay, suppressed by $G$-parity, with relative probability $B(\rho\to 3\pi) = (1.01\pm^{0.54}_{0.36}\pm 0.034) \times 10^{-4}$.