Observation of $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ in the amplitude analysis of $D^{+} \to K_{S}^{0}\pi^+\eta$

TL;DR

This paper reports the first amplitude analysis of the decay D+ to K_S^0 pi+ eta, observing the decay D+ to K_S^0 a_0(980)+ and measuring its branching fraction along with related decay modes, providing insights into W-emission amplitudes and final-state interactions.

Contribution

It presents the first amplitude analysis of D+ to K_S^0 pi+ eta and measures the branching fractions of key decay modes involving a_0(980)+, advancing understanding of decay mechanisms.

Findings

Observation of D+ to K_S^0 a_0(980)+ decay.

Measurement of the absolute branching fraction of D+ to K_S^0 pi+ eta.

Determination of product branching fractions involving a_0(980)+ and K_0^*(1430)^0.

Abstract

We perform for the first time an amplitude analysis of the decay $D^{+}\to K_{S}^{0}\pi^+\eta$ and report the observation of the decay $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ using 2.93 fb$^{-1}$ of $e^+e^-$ collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation free decay among $D$ to $a_{0}(980)$-pseudoscalar, $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ is the ideal decay to extract the contributions of the external and internal $W$-emission amplitudes involving $a_{0}(980)$ and study the final-state interactions. The absolute branching fraction of $D^{+}\to K_{S}^{0}\pi^+\eta$ is measured to be $(1.27\pm0.04_{\rm stat.}\pm0.03_{\rm syst.})\%$. The product branching fractions of $D^{+}\to K_{S}^{0}a_{0}(980)^{+}$ with $a_{0}(980)^{+}\to \pi^+\eta$ and $D^{+}\to \pi^+ K_0^*(1430)^0$ with $K_0^*(1430)^0\to K_{S}^{0}\eta$ are measured to be $(1.33\pm0.05_{\rm stat.}\pm0.04_{\rm syst.})\%$ and $(0.14\pm0.03_{\rm stat.}\pm0.01_{\rm syst.})\%$, respectively.