Search for $f_1(1285) \to \pi^+\pi^-\pi^0$ decay with VES detector

TL;DR

This paper reports the observation of the isospin violating decay of the $f_1(1285)$ meson into three pions, measured at the VES detector, providing insights into meson decay processes.

Contribution

First measurement of the $f_1(1285) o ext{3 pions}$ decay ratio in diffractive reactions at multiple energies.

Findings

Decay observed with a ratio of about 1.4% relative to a known decay channel.

Provides experimental data on isospin violation in meson decays.

Confirms the occurrence of the $f_1(1285)$ decay into three pions.

Abstract

The isospin violating decay $f_1(1285)\to\pi^+\pi^-\pi^0$ has been studied at VES facility. This study is based at the statistics acquired in $\pi^- Be$ interactions at 27, 36.6 and 41 GeV/c in diffractive reaction $\pi^- N \to (f_1 \pi^-) N$. The $f_1(1285) \to \pi^+\pi^-\pi^0$ decay is observed. The ratio of decay probabilities $BR(f_1(1285) \to \pi^+\pi^-\pi^0)$ to $BR(f_1(1285) \to \eta \pi^+\pi^-) \cdot BR(\eta \to \gamma\gamma)$ is $\sim\:1.4%$.