Abstract
Precision measurements of superallowed Fermi -decay transitions, particularly for the lightest superallowed emitters and , set stringent limits on possible scalar current contributions to the weak interaction. In the present work, a discrepancy between recent measurements of the half-life is addressed through two high-precision half-life measurements, via -ray photopeak and counting, that yield consistent results for the half-life of and , respectively. The latter is the most precise superallowed -decay half-life measurement reported to date and the first to achieve a relative precision below . A fit to the world superallowed -decay data including the half-life measurements reported here yields (68% C.L.) for the Fierz interference term and for the ratio of the weak scalar to vector couplings assuming left-handed neutrinos.
- Received 10 February 2016
DOI:https://doi.org/10.1103/PhysRevLett.116.172501
© 2016 American Physical Society