Superallowed 0+ to 0+ nuclear beta decays: A new survey with precision tests of the conserved vector current hypothesis and the standard model
arXiv:0812.1202 · doi:10.1103/PhysRevC.79.055502
Abstract
A new critical survey is presented of all half-life, decay-energy and branching-ratio measurements related to 20 0+ to 0+ beta decays. Compared with our last review, there are numerous improvements: First, we have added 27 recently published measurements and eliminated 9 references; of particular importance, the new data include a number of high-precision Penning-trap measurements of decay energies. Second, we have used the recently improved isospin symmetry-breaking corrections. Third, our calculation of the statistical rate function now accounts for possible excitation in the daughter atom. Finally, we have re-examined the systematic uncertainty associated with the isospin symmetry-breaking corrections by evaluating the radial-overlap correction using Hartree-Fock radial wave functions and comparing the results with our earlier calculations, which used Saxon-Woods wave functions; the provision for systematic uncertainty has been changed as a consequence. The new corrected Ft values are impressively constant and their average, when combined with the muon liftime, yields the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, V_{ud} = 0.97425(22). The unitarity test on the top row of the matrix becomes |V_{ud}|^2 + |V_{us}|^2 + |V_{ub}|^2 = 0.99995(61). Both V_{ud} and the unitarity sum have significantly reduced uncertainties compared with our previous survey, although the new value of V_{ud} is statistically consistent with the old one. From these data we also set limits on the possible existence of scalar interactions, right-hand currents and extra Z bosons. Finally, we discuss the priorities for future theoretical and experimental work with the goal of making the CKM unitarity test even more definitive.
36 pages, 11 tables, 9 figures
References in corpus (16)
- High Precision determination of the pi, K, D and D_s decay constants from lattice QCD
- An improved calculation of the isospin-symmetry-breaking corrections to superallowed Fermi beta decay
- Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry
- Low Energy Precision Test of Supersymmetry
- Electroweak Model and Constraints on New Physics
- Kl3 semileptonic form factor from 2+1 flavour lattice QCD
- Isospin-symmetry-breaking corrections to superallowed Fermi beta decay: Formalism and schematic models
- Q_EC values of the Superallowed beta Emitters 50Mn and 54Co
- Precise half-life measurement of the 26Si ground state
- Time-separated oscillatory fields for high-precision mass measurements on short-lived Al and Ca nuclides
- Measurements of Charged Kaon Semileptonic Decay Branching Fractions K^+- -> pi^0 mu^+- nu and K+- -> pi^0 e^+- nu and Their Ratio
- Precise Half-Life Measurement of the Superallowed beta emitter 10C
- Progress in Kaon Physics on the Lattice
- Variations on a theme by Skyrme
- Analytical approaches to the calculation of f+(0)
- Theoretical progress on V_us on lattice