Observation of $D^{+}\to K_S^0{\pi }^0{\mu }^{+}{\nu }_{\mu }$, Test of Lepton Flavor Universality and First Angular Analysis of $D^{+}\to {\bar{K}}^{\ast }(892{)}^0{\ell }^{+}{\nu }_{\ell }$

BESIII Collaboration, M. Ablikim, M. N. Achasov +688

We report a study of the semileptonic decays $D^{+}\to K_S^0{\pi }^0{\ell }^{+}{\nu }_{\ell }$ ($\ell =e,\mu$) based on $20.3{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at the center-of-m…