Speaker
Dr
Mikhail Gorshteyn
(Mainz University)
Description
Current most precise knowledge of the value of $V_{ud}$ is obtained from the analysis of a number of superallowed nuclear $\beta$-decays. At present, the main limitation in precision of this determination is due to radiative corrections, more specifically the "inner" $\gamma W$-box correction that is independent of the electron spectrum but depends on hadronic structure. A novel dispersion formulation of the $\gamma W$-box is developed. It allows to test the validity and improve the previous evaluation of Marciano and Sirlin, which was based on several semi-empiric assumptions. Further effects, such as possible effects of the nuclear excitations both on inner and outer corrections are discussed.
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Primary author
Dr
Mikhail Gorshteyn
(Mainz University)
