arXiv:1401.2114·v1·Nuclear Experiment
The beta decay of 38Ca: Sensitive test of isospin symmetry-breaking corrections from mirror superallowed 0+-to-0+ transitions
H.I. Park🇺🇸 · J.C. Hardy🇺🇸 · V.E. Iacob🇺🇸 · M. Bencomo🇺🇸 · L. Chen🇺🇸 · V Horvat🇺🇸 · N. Nica🇺🇸 · B.T. Roeder🇺🇸 · E. Simmons🇺🇸 · R.E. Tribble🇺🇸 · I.S. Towner🇺🇸
Abstract
We report the first branching-ratio measurement of the superallowed 0+-to-0+ beta transition from 38Ca. The result, 0.7728(16), leads to an ft value of 3062.3(68)s with a relative precision of +/-0.2%. This makes possible a high-precision comparison of the ft values for the mirror superallowed transitions, 38Ca-to-38mK and 38mK-to-38Ar, which sensitively tests the isospin symmetry-breaking corrections required to extract Vud, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, from superallowed beta decay. The result supports the corrections currently used, and points the way to even tighter constraints on CKM unitarity.
Comments: 5 pages, 3 figures