Precision measurements and CKM unitarity
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada)
Determinations of vertical bar V{sub ud} vertical bar and vertical bar V{sub us} vertical bar along with their implications for the unitarity test vertical bar V{sub ud} vertical bar {sup 2}+vertical bar V{sub us} vertical bar{sup 2}+vertical bar V{sub ub} vertical bar{sup 2}=1 are discussed. The leading two-loop radiative corrections to neutron {beta} decay are evaluated and used to derive a refined relationship vertical bar V{sub ud} vertical bar{sup 2}{tau}{sub n}(1+3g{sub A}{sup 2})=4908(4) s. Employing vertical bar V{sub ud} vertical bar=0.9740(5) from superallowed nuclear decays and the measured neutron lifetime {tau}{sub n}=885.7(7) s leads to the precise prediction g{sub A}=1.2703(8) which is compared with current direct experimental values. Various extractions of vertical bar V{sub us} vertical bar are described and updated. The long accepted Particle Data Group value of vertical bar V{sub us} vertical bar from fitted K{sub e3} decay rates suggests a deviation from CKM unitarity but it is contradicted by more recent experimental results which confirm unitarity with good precision. An outlook for possible future advances is given.
- OSTI ID:
- 20705585
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 70, Issue 9; Other Information: DOI: 10.1103/PhysRevD.70.093006; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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