Observation of the Dalitz Decay $D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}$

TL;DR

This paper reports the first observation of the Dalitz decay $D_{s}^{*+} o D_{s}^{+} e^{+} e^{-}$, measuring its branching ratio relative to the radiative decay, confirming theoretical predictions with a significance of 5.3 sigma.

Contribution

First experimental observation of the Dalitz decay of $D_{s}^{*+}$ meson, providing a new measurement of its branching ratio relative to the radiative decay.

Findings

Observation significance of 5.3 sigma.

Measured ratio of branching fractions: approximately 0.72.

Results align with theoretical expectations.

Abstract

Using 586 $\textrm{pb}^{-1}$ of $e^{+}e^{-}$ collision data acquired at $\sqrt{s}=4.170$ GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of $D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}$ with a significance of $5.3 \sigma$. The ratio of branching fractions $\calB(D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}) / \calB(D_{s}^{*+} \to D_{s}^{+} \gamma)$ is measured to be $[ 0.72^{+0.15}_{-0.13} (\textrm{stat}) \pm 0.10 (\textrm{syst})]%$, which is consistent with theoretical expectations.