Physical Review D, vol.110, no.11, 2024 (SCI-Expanded)
By analyzing e+e- annihilation data corresponding to an integrated luminosity of 7.93 fb-1, collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we search for the semileptonic decays D0→K-ηe+νe, D+→KS0ηe+νe and D+→ηηe+νe for the first time. We present evidence for D0→K-ηe+νe with a significance of 3.3σ. The branching fraction of D0→K-ηe+νe is measured to be (0.84-0.34+0.29±0.22)×10-4. No significant signals are observed for the decays D+→KS0ηe+νe and D+→ηηe+νe and we set the upper limits on their branching fractions.