FCNC effects in a minimal theory of fermion masses

Buras, Andrzej J.; Grojean, Christophe; Pokorski, S.; Ziegler, Robert

doi:10.1007/jhep08(2011)028

Cited by 38 publications

(38 citation statements)

References 52 publications

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“…17 However, it was pointed out in [96,156] that these unwanted effects can be avoided thanks to the Goldstone nature of these scalars, as long as the embedding of the SM fermions into the global symmetries of the strong sector only allows for a single Yukawa-type operatorq L q R F(h, H ), thus enforcing the MFV structure in the scalar interactions. 18 16 Other relevant effects which could also give rise to important constraints on m arise from flavor transitions mediated by the Z [155]. 17 Higgs mediated FCNCs will arise from the operatorsq i Hq j H † H .…”

Section: Anarchic Partial Compositenessmentioning

confidence: 99%

Composite Higgses

2014

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For the closing article in this volume on supersymmetry, we consider the alternative options to SUSY theories: we present an overview of composite Higgs models in light of the discovery of the Higgs boson. The small value of the physical Higgs mass suggests that the Higgs quartic is likely loop generated; thus models with tree-level quartics will generically be more tuned. We classify the various models (including bona fide composite Higgs, little Higgs, holographic composite Higgs, twin Higgs and dilatonic Higgs) based on their predictions for the Higgs potential, review the basic ingredients of each of them, and quantify the amount of tuning needed, which is not negligible in any model. We explain the main ideas for generating flavor structure and the main mechanisms for protecting against large flavor violating effects, and we present a summary of the various coset models that can result in realistic pseudo-Goldstone Higgses. We review the current experimental status of such models by discussing the electroweak precision, flavor, and direct search bounds, and we comment on the UV completions of such models and on ways to incorporate dark matter.

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Section: Anarchic Partial Compositenessmentioning

confidence: 99%

Composite Higgses

2014

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“…In [466] the heavy Yukawa couplings λ U,D have been assumed to be anarchical O(1) real numbers which allowed a first look at the phenomenological implications. In [42] the so called TUM (Trivially Unitary Model) was studied in more detail.…”

Section: New Vectorlike Fermions: a Minimal Theory Of Fermion Massesmentioning

confidence: 99%

“…We end the review of NP models by summarizing the results obtained within a model with vectorlike fermions based on [42,466] that can be seen as a Minimal Theory of Fermion Masses (MTFM). The idea is to explain SM fermion masses and mixings by their dynamical mixing with new heavy vectorlike fermion F .…”

Section: New Vectorlike Fermions: a Minimal Theory Of Fermion Massesmentioning

confidence: 99%

Towards the identification of new physics through quark flavour violating processes

2014

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We outline a systematic strategy which should help in this decade to identify New Physics (NP) beyond the Standard Model (SM) by means of quark flavour violating processes and thereby to extend the picture of short distance physics down to the scales as short as 10 −20 m and even shorter distance scales corresponding to energies of 100 TeV. Rather than using all possible flavour violating observables that will be measured in the coming years at the LHC, SuperKEKB and in Kaon physics dedicated experiments at CERN, J-PARC and Fermilab, we concentrate on those observables that are theoretically clean and very sensitive to NP. Assuming that the data on the selected observables by us will be very precise, we stress the importance of correlations between these observables as well as of future precise calculations of non-perturbative parameters by means of lattice QCD simulations with dynamical fermions. Our strategy consists of twelve steps which we will discuss in detail illustrating possible outcomes with the help of the SM, models with constrained Minimal Flavour Violation (CMFV), MFV at large and models with tree-level FCNCs mediated by neutral gauge bosons and scalars. We also briefly summarize the status of a number of concrete models. We propose DNA-charts that exhibit correlations between flavour observables in different NP scenarios. The models with new left-handed and/or right-handed currents and non-MFV interactions can be distinguished transparently in this manner. We emphasize the important role of the stringent CMFV relations between various observables as standard candles of flavour physics. The pattern of deviations from these relations may help in identifying the correct NP scenario. The success of this program will be very much facilitated through direct signals of NP at the LHC even if LHC will not be able to probe the physics at scales shorter than 4×10 −20 m. We also emphasize the importance of lepton flavour violation, electric dipole moments and (g − 2) e,µ in these studies.

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“…This holds not only for gauge flavour symmetries, that we are discussing in this paper, but also for global flavour symmetries. Indeed, in these models the new exotic fermions and their mixing with the SM ones account for the mass spectrum of the SM fermions (see [36] and references therein). This typically happens through a fermion see-saw mechanism where the small masses of the SM fermions are explained by the large masses of their corresponding exotic fermions.…”

Section: Notation and Fermion See-saw Mechanismmentioning

confidence: 99%

The impact of flavour changing neutral gauge bosons on $ \bar{B} \to {X_s}\gamma $

Buras

Merlo

Stamou

2011

J. High Energ. Phys.

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Abstract:The branching ratio of the rare decay B → X s γ provides potentially strong constraints on models beyond the Standard Model. Considering a general scenario with new heavy neutral gauge bosons, present in particular in Z and gauge flavour models, we point out two new contributions to the B → X s γ decay. The first one originates from one-loop diagrams mediated by gauge bosons and heavy exotic quarks with electric charge −1/3. The second contribution stems from the QCD mixing of neutral current-current operators generated by heavy neutral gauge bosons and the dipole operators responsible for the B → X s γ decay. The latter mixing is calculated here for the first time. We discuss general sum rules which have to be satisfied in any model of this type. We emphasise that the neutral gauge bosons in question could also significantly affect other fermion radiative decays as well as non-leptonic two-body B decays, / , anomalous (g − 2) µ and electric dipole moments.

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FCNC effects in a minimal theory of fermion masses

Cited by 38 publications

References 52 publications

Composite Higgses

Composite Higgses

Towards the identification of new physics through quark flavour violating processes

The impact of flavour changing neutral gauge bosons on $ \bar{B} \to {X_s}\gamma $

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