Using $7.33{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data taken with the BESIII detector at the BEPCII collider, we report the first experimental study of the purely leptonic decay $D_s^{*+}\to e^{+}{\nu }_e$. Our data contain a signal of this decay with a statistical significance of $2.9\sigma$. The branching fraction of $D_s^{*+}\to e^{+}{\nu }_e$ is measured to be $({2.1}_{{-0.9}_{\mathrm{stat}}}^{+1.2}\pm {0.2}_{\mathrm{syst}})\times {10}^{-5}$, corresponding to an upper limit of $4.0\times {10}^{-5}$ at the 90% confidence level. Taking the total width of the $D_s^{*+}$ [$(0.070\pm 0.028)\mathrm{keV}$] predicted with the radiative $D_s^{*+}$ decay from the lattice QCD calculation as input, the decay constant of the $D_s^{*+}$ is determined to be $f_{D_s^{*+}}=({214}_{{-46}_{\mathrm{stat}}}^{+61}\pm 44_{\mathrm{syst}})\mathrm{MeV}$, corresponding to an upper limit of 354 MeV at the 90% confidence level.

• Received 25 April 2023
• Revised 25 July 2023
• Accepted 5 September 2023

DOI:https://doi.org/10.1103/PhysRevLett.131.141802

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Published by the American Physical Society