Amplitude analysis and branching fraction measurement of the decay \boldmath $D_{s}^{+} \to K^+\pi^{+}\pi^{-}\pi^{0}$

TL;DR

This paper reports the first amplitude analysis and precise measurement of the branching fraction of the decay $D_{s}^{+} o K^+ ho^+ o K^+\pi^+\pi^0$, revealing decay sub-structures and dominant intermediate processes.

Contribution

It provides the first amplitude analysis of this decay mode and measures its absolute branching fraction with improved accuracy.

Findings

Dominant process is $D_s^+ o K^{*0} ho^+$ with 40.5% fit fraction.

Measured branching fraction is approximately 9.75 x 10^{-3}.

Identified sub-structures in the decay for the first time.

Abstract

The singly Cabibbo-suppressed decay $D_{s}^{+} \to K^+\pi^{+}\pi^{-}\pi^{0}$ is observed, using a data set corresponding to an integrated luminosity of 6.32 $\rm fb^{-1}$ recorded by the BESIII detector at the centre-of-mass energies between 4.178 and 4.226 GeV. The first amplitude analysis of $D_{s}^{+} \to K^+\pi^{+}\pi^{-}\pi^{0}$ reveals the sub-structures in this decay and determines the fractions and relative phases of different intermediate processes. The dominant intermediate process is $D_s^+ \to K^{*0}\rho^+$, with a fit fraction of $(40.5\pm2.8_{\rm{stat.}}\pm1.5_{\rm{syst.}})\%$. With the detection efficiency based on our amplitude analysis, the absolute branching fraction for $D_{s}^{+} \to K^+\pi^{+}\pi^{-}\pi^{0}$ is measured to be $(9.75\pm0.54_{\rm{stat.}}\pm0.17_{\rm{syst.}})\times 10^{-3}$.