2018/06/30 by Stephen F. King
Physics and Astronomy · #CP violation #Fermion #Lepton #Mixing (physics) #Neutrino Physics Research #Particle physics theoretical and experimental studies #Physics beyond the Standard Model #Quantum Chromodynamics and Particle Interactions #Quark #Universality (dynamical systems) #Yukawa potential #hep-ph
paper · pdf · doi:10.1007/jhep09(2018)069
published as JHEP 1809 (2018) 069 · Minor corrections to phenomenology section to match published version. 19 pages, 4 figures
openalex created_date 2018/06/21 · openalex publication_date 2018/09/01 · arxiv created 2018/10/10 · arxiv updated 2018/10/11 · openalex updated_date 2026/08/05
A bstract We explore the possibility that the semi-leptonic B decay ratios RK(*) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mfenced> <mml:mo>*</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> which violate μ − e universality are related to the origin of the fermion Yukawa couplings in the Standard Model. Some time ago, a vector-like fourth family (without a Z ′) was used to generate fermion mass hierarchies and mixing patterns without introducing any family symmetry. Recently the idea of inducing flavourful Z ′ couplings via mixing with a vector-like fourth family which carries gauged U(1)′ charges has been proposed as a simple way of producing controlled flavour universality violation while elegantly cancelling anomalies. We show that the fusion of these two ideas provides a nice connection between RK(*) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mfenced> <mml:mo>*</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> and the origin of Yukawa couplings in the quark sector. However the lepton sector requires some tuning of Yukawa couplings to obtain the desired coupling of Z ′ to muons.