# Search for the decay $D_s^+\rightarrow \gamma e^+\nu_e$

## TL;DR

This paper reports the first search for the rare decay $D_s^+ o ext{gamma} e^+
u_e$ using BESIII data, setting an upper limit on its branching fraction due to no observed evidence.

## Contribution

It presents the first experimental search for the decay $D_s^+ o ext{gamma} e^+
u_e$ and establishes an upper limit on its branching fraction.

## Key findings

- No evidence for the decay was observed.
- An upper limit of $ ext{Br}(D_s^+ o ext{gamma} e^+
u_e)<1.3 imes 10^{-4}$ was set.
- The result constrains theoretical models of radiative leptonic $D_s^+$ decays.

## Abstract

A search for the rare radiative leptonic decay $D_s^+\to\gamma e^+\nu_e$ is performed for the first time using electron-positron collision data corresponding to an integrated luminosity of 3.19 fb$^{-1}$, collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the $D_s^+\to\gamma e^+\nu_e$ decay is seen and an upper limit of $\mathcal B(D_s^+\to\gamma e^+\nu_e)<1.3\times 10^{-4}$ is set on the partial branching fraction at a 90\% confidence level for radiative photon energies $E_{\gamma}^*>0.01$~GeV.