Abstract
A new survey of all world data on superallowed decays provides demanding tests of, and tight constraints on, the weak interaction. In confirmation of the conserved vector current hypothesis, the vector coupling constant is demonstrated to be constant to better than three parts in , and any induced scalar current is limited to in electron rest-mass units. Any possible fundamental scalar current is similarly limited to . The superallowed data also determine the up-down element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix to be . With Particle Data Group values for and , the top-row test of CKM unitarity yields ; if comes instead from two recent results on decay, this sum becomes 0.9996(11). Either unitarity result can be used to constrain the possible existence of right-hand currents.
- Received 13 December 2004
DOI:https://doi.org/10.1103/PhysRevLett.94.092502
©2005 American Physical Society