Fermi matrix element with isospin breaking

Abstract

Prompted by the level of accuracy now being achieved in tests of the unitarity of the CKM matrix, we consider the possible modification of the Fermi matrix element for the $\beta$-decay of a neutron, including possible in-medium and isospin violating corrections. While the nuclear modifications lead to very small corrections once the Behrends-Sirlin-Ademollo-Gatto theorem is respected, the effect of the $u-d$ mass difference on the conclusion concerning $V_{ud}$ is no longer insignificant. Indeed, we suggest that the correction to the value of $|V_{ud}{|}^2+|V_{us}{|}^2+|V_{ub}{|}^2$ is at the level of $10^{-4}$.

References in corpus (4)

• The role of nucleon structure in finite nuclei
• Nucleon and hadron structure changes in the nuclear medium and impact on observables
• Isospin Breaking in Neutron $\beta$-decay and SU(3) Violation in Semi-leptonic Hyperon Decays
• Effect of Nucleon Structure Variation in Super-allowed Fermi Beta-decay

Cited by in corpus (6)

• Quark-Meson-Coupling (QMC) model for finite nuclei, nuclear matter and beyond
• The Standard Model theory of neutron beta decay
• Charge Symmetry Breaking Effects on Neutron Beta Decay in Non-Relativistic Quark Models
• Quark mass difference effects in hadronic Fermi matrix elements from first principles
• Lambda beta-decay in-medium
• Effect of isoscalar and isovector scalar fields on baryon semileptonic decays in nuclear matter