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Wrinkles in the Froggatt-Nielsen Mechanism and Flavorful New Physics
High Energy Physics - Phenomenology · Submitted 2 Aug 2023
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We show that an effective way to keep track of these changes is by using the new spurions of the $\mathrm{U}(3)^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model.
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The abstract, sentence by sentence
When the Froggatt-Nielsen mechanism is used to explain the Standard Model flavor hierarchy, new physics couplings are also determined by the horizontal symmetry. However, additional symmetries or dynamics in the UV can sometimes lead to a departure from this na\"ive scaling for the new physics couplings. We show that an effective way to keep track of these changes is by using the new spurions of the $\mathrm{U}(3)^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model. As a concrete realization, we consider two flavor spurions of the $S_1$ leptoquark, and demonstrate that wrinkles can be used to make an enhanced value of $\textrm{BR}(B^+ \to K^+\nu\bar{\nu})$ consistent with other flavor observables. We also present example UV models that realize wrinkles, and comment on choosing consistent charges in ordinary Froggatt-Nielsen models without the typical monotonicity condition.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | When the Froggatt-Nielsen mechanism is used to explain the Standard Model flavor hierarchy, new physics couplings are also determined by the horizontal symmetry. | background 1.00 | 0.06 | 0.05 | asserted 1.00 |
| s1 | However, additional symmetries or dynamics in the UV can sometimes lead to a departure from this na\"ive scaling for the new physics couplings. | background 0.74 | 0.06 | 0.04 | hedged possibility 0.99 |
| s2 | We show that an effective way to keep track of these changes is by using the new spurions of the $\mathrm{U}(3)^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model. | method 0.70 | 0.92 | 0.51 | asserted 0.97 |
| s3 | As a concrete realization, we consider two flavor spurions of the $S_1$ leptoquark, and demonstrate that wrinkles can be used to make an enhanced value of $\textrm{BR}(B^+ \to K^+\nu\bar{\nu})$ consistent with other flavor observables. | result 0.52 | 0.94 | 0.33 | asserted 0.94 |
| s4 | We also present example UV models that realize wrinkles, and comment on choosing consistent charges in ordinary Froggatt-Nielsen models without the typical monotonicity condition. | contribution 0.96 | 0.90 | 0.10 | asserted 0.92 |
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The paper
Original abstract
When the Froggatt-Nielsen mechanism is used to explain the Standard Model flavor hierarchy, new physics couplings are also determined by the horizontal symmetry. However, additional symmetries or dynamics in the UV can sometimes lead to a departure from this na\"ive scaling for the new physics couplings. We show that an effective way to keep track of these changes is by using the new spurions of the $\mathrm{U}(3)^5$ global flavor symmetry, where we parameterize extra suppression or enhancement factors, referred to as wrinkles, using the same power counting parameter as in the original Froggatt-Nielsen model. As a concrete realization, we consider two flavor spurions of the $S_1$ leptoquark, and demonstrate that wrinkles can be used to make an enhanced value of $\textrm{BR}(B^+ \to K^+\nu\bar{\nu})$ consistent with other flavor observables. We also present example UV models that realize wrinkles, and comment on choosing consistent charges in ordinary Froggatt-Nielsen models without the typical monotonicity condition.
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References
How the literature uses it
15 arXiv papers cite this in 15 sentences
Papers citing it · 7 sentences without a confident label
Uses its data or values 2 papers
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However, a first measurement by Belle II of the branching ratio $ℬ(B^+→K^+νν̅) = (2.3±0.7)×10^-5$ [ref] , is $2.7σ$ higher than the SM expectation $ℬ(B^+→K^+ νν̅)_SM=(5.58±0.38)×10^-6$ [ref] , and has revived interest in NC $B$ decays [ref] ; an earlier upper limit by Belle II [ref] also led to a flurry of theoretical activity [ref] .
$B \to K \nu\bar\nu$, MiniBooNE and muon $g-2$ anomalies from a dark sector · Introduction · 0.88
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Combining this result with earlier measurements from BaBar [ref] and Belle [ref] , the weighted average branching ratio (BR) is determined to be [equation] This measurement deviates from the standard model (SM) prediction, $B(B^+→K^+ νν̅)^SM=(4.92±0.30) ×10^-6$ [ref] , by $2.7 σ$, suggesting a possible manifest of new physics in the $b→s E$ transitions [ref] .
Leptoquark-mediated Dirac neutrino mass and its impact on $B \to K \nu \bar{\nu}$ and $K \to \pi \nu \bar{\nu}$ decays · Introduction · 0.97
Cites it as background 6 papers
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This type of work, involving different types of Abelian flavour symmetries, has been studied in various contexts [ref] .
Explaining Fermions Mass and Mixing Hierarchies through $U(1)_X$ and $Z_2$ Symmetries · Introduction · 0.97
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See also earlier discussions [ref] of the slight excess indicated by the earlier weighted average [ref] .
Scalar dark matter explanation of the excess in the Belle II $B^+\to K^+ +$ invisible measurement · Introduction · 0.94
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The assumption of an underlying Beyond the Standard Model (BSM) explanation for these hierarchies may provide a valuable hint as to the nature of new physics, and there has been no lack of effort in this direction; Refs. [ref] constitute a representative selection of early and recent examples.
Flavor Hierarchies From SU(2) Flavor and Quark-Lepton Unification · Introduction · 0.98
What it cites · 147 sentences without a confident label
Uses the method or tool of 10 papers
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See Refs. [ref] for details of the calculation.
Electric Dipole Moments in Natural Supersymmetry · Dipole Moments · 0.96
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See Refs. [ref] for details of the calculation.
Combined explanations of $(g-2)_{\mu,e}$ and implications for a large muon EDM · Dipole Moments · 0.96
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See Refs. [ref] for details of the calculation.
Interpreting the Electron EDM Constraint · Dipole Moments · 0.96
Uses data or values from 16 papers
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We set a constraint on the leptoquark mass by demanding that the total predicted branching ratio (including the SM contribution) be less than the $2σ$ upper limit of the measured branching ratio in Ref. [ref] : $BR(K^+ →π^+νν̅) < 1.88 ×10^-10$.
Measurement of the very rare $K^+\rightarrow\pi^+\nu\bar{\nu}$ decay · K to pi nu nu · 0.99
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Following Ref. [ref] , we take $κ_+ = (5.27 ±0.03) ×10^-11$ and $κ_L = (2.27 ±0.01) ×10^-10$.
New strategies for New Physics search in B -> K* nu anti-nu, B -> K nu anti-nu and B -> X(s) nu anti-nu decays · K to pi nu nu · 1.00
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The projected future sensitivity of $ΔC_B_s = 0.026$ is taken from Ref. [ref] , based on projections of HL-LHC results and Belle II results with $50 ab^-1$ integrated luminosity.
Opportunities in Flavour Physics at the HL-LHC and HE-LHC · Predictions for Future Measurements · 0.99
Cites as support 2 papers
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This conclusion is also corroborated by Refs. [ref] , which deduce that the general charge assignments that can explain the SM Yukawa hierarchy can not be anomaly-free by studying general extensions of the SM with a new anomaly-free $U(1)$ gauge group.
General solution to the U(1) anomaly equations · Review of the Froggatt–Nielsen Mechanism · 0.96
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This conclusion is also corroborated by Refs. [ref] , which deduce that the general charge assignments that can explain the SM Yukawa hierarchy can not be anomaly-free by studying general extensions of the SM with a new anomaly-free $U(1)$ gauge group.
An Anomaly-free Atlas: charting the space of flavour-dependent gauged $U(1)$ extensions of the Standard Model · Review of the Froggatt–Nielsen Mechanism · 0.96
Cites as background 43 papers
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The two most popular solutions to this puzzle are (i) the Froggatt–Nielsen (FN) mechanism and its variations [ref] , and (ii) extra dimensional models where an $𝒪(1)$ difference in the bulk masses of fermions gives rise to an exponential hierarchy between the observed masses in the IR [ref] .
Mass Matrix Models · Aperitif · 0.97
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The two most popular solutions to this puzzle are (i) the Froggatt–Nielsen (FN) mechanism and its variations [ref] , and (ii) extra dimensional models where an $𝒪(1)$ difference in the bulk masses of fermions gives rise to an exponential hierarchy between the observed masses in the IR [ref] .
New Tools for Fermion Masses from Extra Dimensions · Aperitif · 0.97
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The two most popular solutions to this puzzle are (i) the Froggatt–Nielsen (FN) mechanism and its variations [ref] , and (ii) extra dimensional models where an $𝒪(1)$ difference in the bulk masses of fermions gives rise to an exponential hierarchy between the observed masses in the IR [ref] .
Fermion Masses, Mixings and Proton Decay in a Randall-Sundrum Model · Aperitif · 0.97
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