Test of Lepton Universality and Measurement of the Form Factors of $ {D}^{0}\to {K}^{*}(892{)}^{-}{\mu }^{+}{\nu }_{\mu }$

One of the main goals of studying semileptonic decays in flavor physics is to gain a better understanding of hadronic transitions in the nonperturbative region of Quantum Chromodynamics. This involves measuring Cabibbo-Kobayashi-Maskawa matrix elements, understanding form factors, and comparing them with theoretical predictions. We report a first study of the semileptonic decay $ {D}^{0}\to {K}^{-}{\pi }^{0}{\mu }^{+}{\nu }_{\mu }$ by analyzing an $ {e}^{+}{e}^{-}$ annihilation data sample of $ 7.93\text{}\text{}{\mathrm{fb}}^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The absolute branching fraction of $ {D}^{0}\to {K}^{-}{\pi }^{0}{\mu }^{+}{\nu }_{\mu }$ is measured for the first time, providing necessary input for extracting the $ c\to s$ Cabibbo-Kobayashi-Maskawa matrix element through this process. This measurement allows us to test lepton flavor universality, with no indication of violation found. Furthermore, a series of hadronic form factors have been determined and compared with theoretical predictions, which will impose stricter constraints on theoretical models.