Amplitude analysis and branching fraction measurement of the decay $D_{s}^{+} \to K^+\pi^+\pi^-$

TL;DR

This paper presents an amplitude analysis of the decay $D_s^+ o K^+ ho^0, ho^0 o \pi^+\pi^-$, measures its branching fraction, and observes several intermediate resonances for the first time, using data from the BESIII detector.

Contribution

It provides the first observation of $f_0(500)$, $f_0(980)$, and $f_0(1370)$ resonances in this decay channel and measures the decay's branching fractions with improved precision.

Findings

Branching fraction of $D_s^+ o K^+\pi^+\pi^-$ measured as $(6.11 extpm0.18_{ m stat.} extpm0.11_{ m syst.}) imes 10^{-3}$

Dominant intermediate processes' branching fractions determined, e.g., $K^+ ho^0$ and $K^*(892)^0 o K^+\pi^-$

First observation of $f_0(500)$, $f_0(980)$, and $f_0(1370)$ in this decay channel

Abstract

Using $6.32$ fb$^{-1}$ of $e^{+}e^{-}$ collision data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay $D^+_s \to K^+\pi^+\pi^-$ and determine the amplitudes of the various intermediate states. The absolute branching fraction of $D^+_s\to K^+\pi^+\pi^-$ is measured to be ($6.11\pm0.18_{\rm stat.}\pm0.11_{\rm syst.})\times 10^{-3}$. The branching fractions of the dominant intermediate processes $D_{s}^{+} \to K^+\rho^0, \rho^0 \to \pi^+\pi^-$ and $D_{s}^{+} \to K^*(892)^0\pi^+, K^*(892)^0 \to K^+\pi^-$ are determined to be $(1.96\pm0.19_{\rm stat.}\pm0.23_{\rm syst.})\times 10^{-3}$ and $(1.85\pm0.12_{\rm stat.}\pm0.13_{\rm syst.})\times 10^{-3}$, respectively. The intermediate resonances $f_0(500)$, $f_0(980)$, and $f_0(1370)$ are observed for the first time in this channel.