Search for the leptonic decays $D^{*+}\to e^+\nu_e$ and $D^{*+}\to \mu^+\nu_\mu$

TL;DR

This paper reports the first search for leptonic decays of the $D^{*+}$ meson into electron and muon neutrinos, setting upper limits on their branching fractions using BESIII data.

Contribution

It provides the first experimental upper limits on the branching fractions of $D^{*+}$ leptonic decays into $e^+ u_e$ and $ u_ u$ channels.

Findings

No significant signals observed for the decays.

Upper limits on branching fractions are $1.1 imes 10^{-5}$ for $e^+ u_e$ and $4.3 imes 10^{-6}$ for $ u_ u$.

Abstract

We present the first search for the leptonic decays $D^{*+}\to e^+\nu_e$ and $D^{*+}\to \mu^+\nu_\mu$ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32~fb$^{-1}$. No significant signal is observed. The upper limits on the branching fractions for $D^{*+}\to e^+\nu_e$ and $D^{*+}\to \mu^+\nu_\mu$ are set to be $1.1 \times 10^{-5}$ and $4.3 \times 10^{-6}$ at 90\% confidence level, respectively.