English

U(2) is Right for Leptons and Left for Quarks

High Energy Physics - Phenomenology 2024-02-28 v2 High Energy Physics - Experiment

Abstract

We posit that the distinct patterns observed in fermion masses and mixings are due to a minimally broken U(2)q+e\mathrm{U}(2)_{q+e} flavor symmetry acting on left-handed quarks and right-handed charged leptons, giving rise to an accidental U(2)5\mathrm{U}(2)^5 symmetry at the renormalizable level without imposing selection rules on the Weinberg operator. We show that the symmetry can be consistently gauged by explicit examples and comment on realizations in SU(5)\mathrm{SU}(5) unification. Via a model-independent SMEFT analysis, we find that selection rules due to U(2)q+e\mathrm{U}(2)_{q+e} enhance the importance of charged lepton flavor violation as a probe, where significant experimental progress is expected in the near future.

Keywords

Cite

@article{arxiv.2311.09288,
  title  = {U(2) is Right for Leptons and Left for Quarks},
  author = {Stefan Antusch and Admir Greljo and Ben A. Stefanek and Anders Eller Thomsen},
  journal= {arXiv preprint arXiv:2311.09288},
  year   = {2024}
}

Comments

8 pages, 1 figure. v2: updated discussion of the GUT symmetry

R2 v1 2026-06-28T13:22:32.997Z