We present the first search for the semileptonic decay $D_s^{+}\to {\pi }^0{e}^{+}{\nu }_e$ using 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 $6.32{\mathrm{fb}}^{-1}$. This decay is expected to be sensitive to ${\pi }^0–\eta$ mixing. No significant signal is observed. We set an upper limit of $6.4\times {10}^{-5}$ on the branching fraction at the 90% confidence level.

• Received 28 June 2022
• Accepted 31 October 2022

DOI:https://doi.org/10.1103/PhysRevD.106.112004

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Published by the American Physical Society