Rising through the ranks: flavor hierarchies from a gauged symmetry

Admir Greljo; Anders Eller Thomsen

doi:10.1140/epjc/s10052-024-12556-5

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2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 213
https://doi.org/10.1140/epjc/s10052-024-12556-5

Regular Article - Theoretical Physics

Rising through the ranks: flavor hierarchies from a gauged $SU (2)$ ${\varvec{\mathrm {SU(2)}}}$ symmetry

Admir Greljo¹ and Anders Eller Thomsen¹^,2^b

¹ Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland
² Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, 3012, Bern, Switzerland

^b thomsen@itp.unibe.ch

Received: 2 October 2023
Accepted: 14 February 2024
Published online: 29 February 2024

Abstract

We propose an economical model to address the mass hierarchies of quarks and charged leptons. The light generations of the left-handed fermions form doublets under an $SU (2)$ $\textrm{SU}(2)$ flavor symmetry, which is gauged. The generational hierarchies emerge from three independent rank-one contributions to the Yukawa matrices: one is a renormalizable contribution, the second is suppressed by a mass ratio, and the last by an additional loop factor. The model is renormalizable, features only a handful of new fields, and is remarkably simple compared to typical completions of gauged flavor symmetries or Froggatt–Nielsen. The model has a rich phenomenology, and we highlight promising signatures, especially in the context of K and B meson physics. This includes an interpretation of the latest $B^{+} \to K^{+} ν \bar{ν}$ $B^+ \rightarrow K^+ \nu \bar{\nu }$ measurement from Belle II.

© The Author(s) 2024

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