A realistic U(2) model of flavor

Linster, Matthias; Ziegler, Robert

doi:10.1007/jhep08(2018)058

Cited by 49 publications

(50 citation statements)

References 53 publications

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“…The best fit values together with the experimental and theoretical predictions are presented in Table II. We note that our successful results might be anticipated from the qualitatively similar Yukawa textures obtained in U(2) flavor models [15,18], a further example of the similarities between T ′ models and U(2) models that was the focus of Refs. [1,2].…”

Section: B Fit To Quarks and Charged Leptonssupporting

confidence: 53%

“…(ii ) We address the strong CP problem by promoting an Abelian factor that is required in the model from a Z 3 symmetry to an anomalous U(1) symmetry. This leads to a flavorful axion [12] (also called a flaxion [13], or axi-flavon [14][15][16], in the literature), which leads to more stringent lower bounds on the flavor scale M F than in our previous study (as well as new avenues for discovery). The possibility of flavored axions due to a continuous Abelian factor in a T ′ flavor model was considered in a supersymmetric model in Ref.…”

Section: Introductionmentioning

confidence: 77%

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Flavor from the double tetrahedral group without supersymmetry: Flavorful axions and neutrinos

Carone

Merchand

2019

Phys. Rev. D

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We extend the work of Carone, Chaurasia and Vasquez on non-supersymmetric models of flavor based on the double tetrahedral group. Three issues are addressed: (1) the sector of flavorsymmetry-breaking fields is simplified and their potential studied explicitly, (2) a flavorful axion is introduced to solve the strong CP problem and (3) the model is extended to include the neutrino sector. We show how the model can accommodate the strong hierarchies manifest in the charged fermion Yukawa matrices, while predicting a qualitatively different form for the light neutrino mass matrix that is consistent with observed neutrino mass squared differences and mixing angles.The structure of the fermion Yukawa couplings in the standard model may result from the sequential breaking of a horizontal discrete family symmetry. Long ago, Aranda, Carone and Lebed [1, 2] showed how the double tetrahedral group T ′ could be used to construct successful supersymmetric flavor models that are similar to those based on U(2) symmetry [3,4], with or without the assumption of conventional supersymmetric grand unification. For other early work on T ′ as a flavor symmetry, see Ref. [5]. Many other authors have since explored the use of T ′ symmetry in models that aim to address the flavor structure of the standard model [6].Much of the work on T ′ flavor models has assumed weak-scale supersymmetry, to stabilize the hierarchy between the weak scale and the grand unified or Planck scale. Over the past decade, however, there has been no direct evidence for superpartners at the LHC, nor indirect evidence in the form of a convincing pattern of deviations from the predictions of the standard model for some subset of its observables. While one cannot exclude the possibility that supersymmetry is present and just beyond the reach of current experiments (a statement that applies to any new physics that has a decoupling limit), the current state of affairs has motivated a greater open-mindedness towards consideration of non-supersymmetric extensions of the standard model. For example, the possibility that the standard model could arise consistently from a string theory without supersymmetry has been discussed in Ref. [7].The hierarchies between mass scales might result from dynamical mechanisms (for example, cosmic relaxation [8] or Nnaturalness [9]), or anthropic selection [10]. On the other hand, the fundamental mass scales found in nature may simply be random and fine tuned, for reasons that are obscure to us at present. In this work, we assume the absence of supersymmetry and focus on phenomenological issues, while remaining agnostic on the question of naturalness.The purpose of the present work is to further explore the possibility of nonsupersymmetric models of flavor based on T ′ symmetry, following a study by Carone, Chaurasia and Vasquez [11]. In Ref. [11], a nonsupersymmetric T ′ model was presented in which the flavor scale M F was treated as a free parameter. (There is less motivation to link the flavor scale to a grand unified scale in a frame...

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Section: B Fit To Quarks and Charged Leptonssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 77%

Flavor from the double tetrahedral group without supersymmetry: Flavorful axions and neutrinos

Carone

Merchand

2019

Phys. Rev. D

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“…While in the simplest scenario PQ and FN symmetries are identified [53][54][55], PQ could also be a subgroup of a larger flavor symmetry; see, e.g., Refs. [56][57][58][59][60][61][62][63][64][65]. Finally, flavored PQ symmetries can arise also in the context of minimal-flavor violation (MFV) [66,67] or as accidental symmetries in models with gauged flavor symmetries [68][69][70][71].…”

Section: Introductionmentioning

confidence: 99%

Quark flavor phenomenology of the QCD axion

et al. 2020

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Axion models with generation-dependent Peccei-Quinn charges can lead to flavor-changing neutral currents, thus motivating QCD axion searches at precision flavor experiments. We rigorously derive limits on the most general effective flavor-violating couplings from current measurements and assess their discovery potential. For two-body decays, we use available experimental data to derive limits on q → q 0 a decay rates for all flavor transitions. Axion contributions to neutral-meson mixing are calculated in a systematic way using chiral perturbation theory and operator product expansion. We also discuss in detail baryonic decays and three-body meson decays, which can lead to the best search strategies for some of the couplings. For instance, a strong limit on the Λ → na transition can be derived from the supernova SN 1987A. In the near future, dedicated searches for q → q 0 a decays at ongoing experiments could potentially test Peccei-Quinn breaking scales up to 10 12 GeV at NA62 or KOTO and up to 10 9 GeV at Belle II or BES III.

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“…Along the lines of what presented recently in ref. [24], a further improvement of this method can be provided by introducing an additional weight to χ 2…”

Section: A Customary Approachmentioning

confidence: 99%

“…In literature, popular approaches aimed at UV-completing the SM with main focus on the flavour puzzle have extensively relied on the existence of "flavons": heavy scalar JHEP03(2021)135 fields whose vacuum expectation value (VEV) yields spontaneous symmetry breaking of a large enough (discrete or continuous) symmetry group, subgroup of G F , responsible of the low-energy fermion mass spectrum and the mixing-angle patterns. Flavons may be considered ubiquitous in the context of Grand Unified Theories [20][21][22][23][24][25] and of stringy UV completions [26][27][28][29][30]. Then, the flavour puzzle may offer a phenomenological handle on those UV theories involving very-high energy dynamics difficult to probe at colliders, that may feature the predicted flavour pattern as a key IR signature of the theory [31,32].…”

Section: Introductionmentioning

confidence: 99%

Minimal Froggatt-Nielsen textures

Fedele

Alessio

Valli

2021

J. High Energ. Phys.

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The flavour problem of the Standard Model can be addressed through the Froggatt-Nielsen (FN) mechanism. In this work, we develop an approach to the study of FN textures building a direct link between FN-charge assignments and the measured masses and mixing angles via unitary transformations in flavour space. We specifically focus on the quark sector to identify the most economic FN models able to provide a dynamical and natural understanding of the flavour puzzle. Remarkably, we find viable FN textures, involving charges under the horizontal symmetry that do not exceed one in absolute value (in units of the flavon charge). Within our approach, we also explore the degree of tuning of FN models in solving the flavour problem via a measure analogous to the Barbieri-Giudice one. We find that most of the solutions do not involve peculiar cancellations in flavour space.

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A realistic U(2) model of flavor

Cited by 49 publications

References 53 publications

Flavor from the double tetrahedral group without supersymmetry: Flavorful axions and neutrinos

Flavor from the double tetrahedral group without supersymmetry: Flavorful axions and neutrinos

Quark flavor phenomenology of the QCD axion

Minimal Froggatt-Nielsen textures

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