Currently, the value of Vud is determined from measurements of superallowed 0+ 0+ nuclear beta decay. It now has a precision of 0.03%. Well over 100 independent measurements of 13 separate superallowed transitions provide a very robust data set, and good agreement among the average results for all 13 transitions confirms the validity of the small theoretical transition-dependent corrections that must be applied in the extraction of the vector coupling constant, G, and of V ud. The superallowed data also yield important and precise confirmation of the Conserved Vector Current (CVC) hypothesis. 2006 American Institute of Physics.
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INTERSECTIONS OF PARTICLE AND NUCLEAR PHYSICS: 9th Conference CIPAN2006