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$|V_{ud}|$ from nuclear $\beta$ decays

J. Hardy, I.S. Towner

in 9th International Workshop on the CKM Unitarity Triangle

Contribution: pdf


At present, the best value for Vud, 0.97420(21), comes from superallowed 0+-to-0+ nuclear beta transitions, of which fourteen have now been measured with high precision. The current status of world data is presented and shown to be robust. The derived Vud value is consistent with the considerably less precise results obtained from beta decays of the neutron, the pion and T = 1/2 mirror nuclei. Nuclear isospin symmetry-breaking corrections appear to be well under control, having been tested by on-going experiments.