Measurement of the absolute branching ratio of the $K^+ \rightarrow \pi^+\pi^-\pi^+(\gamma)$ decay with the KLOE detector

TL;DR

This paper reports a highly precise measurement of the absolute branching ratio for the decay $K^+ ightarrow \pi^+\pi^-\pi^+(\gamma)$ using the KLOE detector, significantly improving previous accuracy.

Contribution

The study provides the most precise measurement to date of the $K^+ ightarrow \pi^+\pi^-\pi^+(\gamma)$ branching ratio, completing the KLOE program of kaon decay measurements.

Findings

Branching ratio measured as 0.05565 with high precision.

Result is about five times more precise than previous measurements.

Measurement confirms and refines the understanding of kaon decay processes.

Abstract

The absolute branching ratio of the $K^+ \rightarrow \pi^+\pi^-\pi^+(\gamma)$ decay, inclusive of final-state radiation, has been measured using $\sim$17 million tagged $K^+$ mesons collected with the KLOE detector at DA$\Phi$NE, the Frascati $\phi$-factory. The result is: \[ BR(K^+ \rightarrow \pi^+\pi^-\pi^+(\gamma)) = 0.05565 \pm 0.00031_{stat} \pm 0.00025_{syst} \] a factor $\simeq$ 5 more precise with respect to the previous result. This work completes the program of precision measurements of the dominant kaon branching ratios at KLOE.