Precision Measurement of Vud from Beta Decays
Dr. Chien-Yeah Seng (Univ. Bonn)

The precision measurement of the top-row Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{ud}$ from beta decays of pion, neutron and nuclei plays an important role in low-energy precision tests of Standard Model (SM) predictions. The recent observation of an apparent deficit of the top-row CKM unitarity has attracted wide attentions and provided hints for physics beyond the Standard Model (BSM). Higher precision for the $V_{ud}$ extraction is needed to confirm (or reject) such an observation; in this talk the referent will discuss some ongoing efforts from the theory and experimental side to achieve this goal.