Natural fermion mass hierarchy and new signals for the Higgs boson

Babu, K. S.; Nandi, S.

doi:10.1103/physrevd.62.033002

Cited by 74 publications

(135 citation statements)

References 16 publications

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“…The neutrino mass is forbidden at d = 5, but appears from effective operators of higher dimension [35,36]. Such an approach is not feasible in models with only the SM Higgs doublet, since (H † H) is a complete singlet and can not carry any charges.…”

Section: Jhep03(2015)040mentioning

confidence: 99%

Systematic classification of two-loop realizations of the Weinberg operator

Sierra

Degée

Dorame

et al. 2015

J. High Energ. Phys.

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We systematically analyze the d = 5 Weinberg operator at 2-loop order. Using a diagrammatic approach, we identify two different interesting categories of neutrino mass models: (i) Genuine 2-loop models for which both, tree-level and 1-loop contributions, are guaranteed to be absent. And (ii) finite 2-loop diagrams, which correspond to the 1-loop generation of some particular vertex appearing in a given 1-loop neutrino mass model, thus being effectively 2-loop. From the large list of all possible 2-loop diagrams, the vast majority are infinite corrections to lower order neutrino mass models and only a moderately small number of diagrams fall into these two interesting classes. Moreover, all diagrams in class (i) are just variations of three basic diagrams, with examples discussed in the literature before. Similarly, we also show that class (ii) diagrams consists of only variations of these three plus two more basic diagrams. Finally, we show how our results can be consistently and readily used in order to construct two-loop neutrino mass models.

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Section: Jhep03(2015)040mentioning

confidence: 99%

Systematic classification of two-loop realizations of the Weinberg operator

Sierra

Degée

Dorame

et al. 2015

J. High Energ. Phys.

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“…The neutrino mass is forbidden or suppressed at d = 5, but appears from effective operators of higher dimension [6,[53][54][55][56][57][58][59][60][61][62][63][64].…”

Section: Introductionmentioning

confidence: 99%

Systematic study of the d = 5 Weinberg operator at one-loop order

Bonnet

Hirsch

Ota

et al. 2012

J. High Energ. Phys.

169

222

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We perform a systematic study of the d = 5 Weinberg operator at the one-loop level. We identify three different categories of neutrino mass generation: (1) finite irreducible diagrams; (2) finite extensions of the usual seesaw mechanisms at one-loop and (3) divergent loop realizations of the seesaws. All radiative one-loop neutrino mass models must fall into one of these classes. Case (1) gives the leading contribution to neutrino mass naturally and a classic example of this class is the Zee model. We demonstrate that in order to prevent that a tree level contribution dominates in case (2), Majorana fermions running in the loop and an additional Z 2 symmetry are needed for a genuinely leading one-loop contribution. In the type-II loop extensions, the Yukawa coupling will be generated at one loop, whereas the type-I/III extensions can be interpreted as loop-induced inverse or linear seesaw mechanisms. For the divergent diagrams in category (3), the tree level contribution cannot be avoided and is in fact needed as counter term to absorb the divergence.

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“…ct are also predicted in the different scenarios of Refs. [16,17], where Yukawa couplings of the light fermions involve higher powers of the Higgs field. In that case however, only very small shifts are expected in the flavor-preserving t " th coupling.…”

Section: Discussionmentioning

confidence: 99%

“…In either case a full, general analysis of Higgs-mediated ÁF ¼ 2 neutral currents was not carried through. Finally, similar flavor-violating effects from the Higgs sector have been considered in [16,17], although in a different context.…”

Section: Introductionmentioning

confidence: 99%

Composite Higgs-mediated flavor-changing neutral current

2009

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We discuss how, in the presence of higher-dimensional operators, the standard model fermion masses can be misaligned in flavor space with the Yukawa couplings to the Higgs boson, even with only one Higgs doublet. Such misalignment results in flavor-violating couplings to the Higgs and hence flavorchanging neutral current processes from tree-level Higgs exchange. We perform a model-independent analysis of such an effect. Specializing to the framework of a composite Higgs with partially composite standard model gauge and fermion fields, we show that the constraints on the compositeness scale implied by K can be generically as strong as those from the exchange of heavy spin-1 resonances if the Higgs is light and strongly coupled to the new states. In the special and well-motivated case of a composite pseudoGoldstone Higgs, we find that the shift symmetry acting on the Higgs forces an alignment of the fermion mass terms with their Yukawa couplings at leading order in the fermions' degree of compositeness, thus implying much milder bounds. As a consequence of the flavor-violating Higgs couplings, we estimate BRðt ! chÞ $ 10 À4 and BRðh ! tcÞ $ 5 Â 10 À3 both for a pseudo-Goldstone (if t R is fully composite) and for a generic composite Higgs. By virtue of the AdS/CFT correspondence, our results directly apply to 5-dimensional Randall-Sundrum compactifications.

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Natural fermion mass hierarchy and new signals for the Higgs boson

Cited by 74 publications

References 16 publications

Systematic classification of two-loop realizations of the Weinberg operator

Systematic classification of two-loop realizations of the Weinberg operator

Systematic study of the d = 5 Weinberg operator at one-loop order

Composite Higgs-mediated flavor-changing neutral current

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