A Domino Theory of Flavor

Abstract

We argue that the fermion masses and mixings are organized in a specific pattern. The approximately equal hierarchies between successive generations, the sizes of the mixing angles, the heaviness of just the top quark, and the approximate down-lepton equality can all be accommodated by many flavor models but can appear ad hoc. We present a simple, predictive mechanism to explain these patterns. All generations are treated democratically and the flavor symmetries are broken collectively by only two allowed couplings in flavor-space, a vector and matrix, with arbitrary O(1) entries. Repeated use of these flavor symmetry breaking spurions radiatively generates the Yukawa couplings with a natural hierarchy. We demonstrate this idea with two models in a split supersymmetric grand unified framework, with minimal additional particle content at the unification scale. Although flavor is generated at the GUT scale, there are several potentially testable predictions. In our minimal model the usual prediction of exact b-tau unification is replaced by the SU(5) breaking relation m_tau / m_b = 3 / 2, in better agreement with observations. Other SU(5) breaking effects in the fermion masses can easily arise directly from the flavor model itself. The symmetry breaking that triggers the generation of flavor necessarily gives rise to an axion, solving the strong CP problem. These theories contain long-lived particles whose decays could give striking signatures at the LHC and may solve the primordial Lithium problems. These models also give novel proton decay signatures which can be probed by the next generation of experiments. Measurement of the various proton decay channels directly probes the flavor symmetry breaking couplings. In this scenario the Higgs mass is predicted to lie in a range near 150 GeV.

33 pages, 11 figures, 5 tables. v2: Refs added, version to appear in PRD

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Cited by in corpus (18)

• A Little Solution to the Little Hierarchy Problem: A Vector-like Generation
• A Supersymmetric One Higgs Doublet Model
• A sharp 141 GeV Higgs prediction from environmental selection
• R-symmetric High Scale Supersymmetry
• Dynamical Supersymmetry Breaking, with Flavor
• Radiatively generated fermion mass hierarchy from flavour non-universal gauge symmetries
• Environmentally Selected WIMP Dark Matter with High-Scale Supersymmetry Breaking
• Split SUSY Radiates Flavor
• Flavor Seesaw Mechanism
• Simple Models of Superconformal Flavor
• Natural Alignment of Quark Flavors and Radiatively Induced Quark Mixings
• Gauged $SU(3{)}_F$ and loop induced quark and lepton masses
• Loop-induced masses for the first two generations with optimum flavour violation
• Radiative Origin of Fermion Mass Hierarchy in Left-Right Symmetric Theory
• Higgs Boson Yukawa Form Factors from Supersymmetric Radiative Fermion Masses
• Recent Progress in Flavor Model Building
• Constrained Flavor Breaking
• Radiative Mass Mechanism: Addressing the Flavour Hierarchy and Strong CP Puzzle