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

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.