International Conference on Precision Physics and Fundamental Physical Constants FFK2023

Electroweak nuclear radii constrain isospin-breaking corrections to Vud

24 May 2023, 17:15

15m

Oral presentation tests and extensions of the Standard Model of elementary particles Wednesday 4

Speaker

Misha Gorshteyn (Mainz University)

Description

The most precise determination of the top-left corner element of the CKM quark mixing matrix $V_{ud}$ is obtained from accurate measurements of superallowed nuclear $\beta$ decays. Among the theoretical ingredients in this determination, the isospin symmetry-breaking (ISB) correction ${\delta }_{\mathrm{C}}$ plays a crucial role in aligning the $Ft$-values across all superallowed transitions. This alignment allows for a joint analysis of many transitions in terms of $V_{ud}$, while remaining misalignments are used to set stringent limits on BSM scalar currents. Until recently, ${\delta }_{\mathrm{C}}$ could not be directly constrained by observables remaining a purely theoretical input, and the respective uncertainty was hard to estimate reliably. In a series of recent works, we construct combinations of the nuclear charge and weak radii which are connected to ${\delta }_{\mathrm{C}}$. These nuclear radii can be obtained experimentally from a combination of muonic atom spectroscopy, isotope shift measurements, and parity violation in electron scattering, and the corresponding experimental uncertainties can be used for a robust, data-driven and model-independent uncertainty on ${\delta }_{\mathrm{C}}$, empowering tests of CKM unitarity and constraints on BSM with nuclear $\beta$ decays.

Presentation materials

Nuclear Radii deltaC FFK Vienna .pdf