Cabibbo Angle Anomaly

Found a interesting paper on ArXiv, Explaining the Cabibbo Angle Anomaly, in which A. Crivelin, summaries ways of explaining the matrix of transition amplitudes for up type quarks being turn to down type quarks of the same of different generations. This Cabibbo Matrix is not unitrary at 3 sigma, but it has to be unitary in fact. Crivelin shows that it could be explained as the weak force being strong in muon decay than in interactions between quarks, 3.4 Sigma discrepancy between the Fermi (Weak force strength) Constants. GCKM F = 0.99925(25) × G muon. So we need a theory that can give muon weak decay slight stronger amplitude, but be the lower for quark decay. Our Axial force does that, the relavent diagram for muon decay, being,

If the axial force constant is A, this makes G muon bigger by (1+A) approximately. We hope to compute the diagram correctly later. The quark decay via the weak force, also picks up an axial force correction. But the correction depends on the axial force charges on the quarks, and for our favourite pick of half on u quarks and minus a half on d quarks, that exactly cancels out. Too explain the muon fermi constant being 1.00075 strong, we need an Axial force constant of one tenth the strength of the electromagnetic field, one tenth the fine structure constant. This is eight time stronger than my guess from renormalation flow, but experimental bound on neutrino neutrino interactions are very weak, and nucleus neutrino interactions, only recently have been measured. The Cabibbo Angle Anomaly is only 3.4 sigma so might disappear with future measurement. The axial force is not the only explination for it, Crivelin lists 6 possible BSM physics that might explain, with the axial force falls into 3.5 SU (2)L Neutral Vector Boson (Z′):. Crivellin also, with others, worked on https://arxiv.org/pdf/2104.07680.pdf, looking at an extra Z` but that force, was massive and coupled to the charged leptons. The axial force couples to neutrinos and quarks, only in our model, thus escaping experimental constraints.