The dynamical composite Higgs

Gersdorff, Gero von; Pontón, Eduardo; Rosenfeld, R.

doi:10.1007/jhep06(2015)119

Cited by 38 publications

(43 citation statements)

References 88 publications

(202 reference statements)

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“…The computation of the diagrams in Fig. 1 leads to a self-consistent condition on the dynamical fermion mass M ψ , 15) where the first factor 2 accounts for the normalisation M ψ ≡ 2 m 1,2 , (−2) is the trace over Weyl spinor indices in the loop, T r[Ω 2 ] = −2N is the trace over hypercolour, and T r[Σ 2 0 ] = −4 the one over flavour. Note that the factors 2N cancel, thanks to the appropriate large-N normalisation of the original couplings κ A,B in Eq.…”

Section: A Scalar Interactions Of Fermion Bilinears and The Mass Gapmentioning

confidence: 99%

“…Alternative ultraviolet completions of composite Higgs models are discussed in Refs. [14][15][16][17].…”

mentioning

confidence: 99%

“…Our analysis builds on an early, enlightening study [8], which employed four-fermion operators to understand the dynamics of this SU (4) × SU (6) model with hypercolour group Sp(2N ), in close analogy with the NJL description of QCD (NJL techniques have been applied to different ultraviolet-complete composite-Higgs models as well [15]). We will provide the first, thorough computation of the spectrum of the meson resonances in this scenario.…”

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confidence: 99%

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Nonperturbative analysis of the spectrum of meson resonances in an ultraviolet-complete composite-Higgs model

et al. 2017

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We consider a vector-like gauge theory of fermions that confines at the multi-TeV scale, and that realizes the Higgs particle as a composite Goldstone boson. The weak interactions are embedded in the unbroken subgroup Sp(4) of a spontaneously broken SU (4) flavour group. The meson resonances appear as poles in the two-point correlators of fermion bilinears, and include the Goldstone bosons plus a massive pseudoscalar η , as well as scalars, vectors and axial vectors. We compute the mass spectrum of these mesons, as well as their decay constants, in the chiral limit, in the approximation where the hypercolour Sp(2N ) dynamics is described by four-fermion operators,à la Nambu-Jona Lasinio. By resumming the leading diagrams in the 1/N expansion, we find that the spin-one states lie beyond the LHC reach, while spin-zero electroweak-singlet states may be as light as the Goldstone-boson decay constant, f ∼ 1 TeV. We also confront our results with a set of available spectral sum rules. In order to supply composite top-quark partners, the theory contains additional fermions carrying both hypercolour and ordinary colour, with an associated flavour symmetry-breaking pattern SU (6)/SO(6). We identify and analyse several non-trivial features of the complete two-sector gauge theory: the 't Hooft anomaly matching conditions; the higher-dimension operator which incorporates the effects of the hypercolour axial-singlet anomaly; the coupled mass-gap equations; the mixing between the singlet mesons of the two sectors, resulting in an extra Goldstone boson η0, and novel spectral sum rules. Assuming that the strength of the four-fermion interaction is the same in the two sectors, we find that the coloured vector and scalar mesons have masses 4f , while the masses of coloured pseudo-Goldstone bosons, induced by gluon loops, are 1.5f . We discuss the scaling of the meson masses with the values of N , of the four-fermion couplings, and of a possible fermion mass.

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Section: A Scalar Interactions Of Fermion Bilinears and The Mass Gapmentioning

confidence: 99%

“…Alternative ultraviolet completions of composite Higgs models are discussed in Refs. [14][15][16][17].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nonperturbative analysis of the spectrum of meson resonances in an ultraviolet-complete composite-Higgs model

et al. 2017

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“…the theories considered in [23][24][25][26][27][28][29][30][31][32]) and associate the Higgs with a pseudo Nambu-Goldstone boson (pNGB) that…”

Section: Model Overviewmentioning

confidence: 99%

Constraining fine tuning in composite Higgs models with partially composite leptons

Barnard

Murnane

Williams

2017

J. High Energ. Phys.

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Minimal Composite Higgs Models (MCHM) have long provided a solution to the hierarchy problem of the Standard Model, yet suffer from various sources of fine tuning that are becoming increasingly problematic with the lack of new physics observations at the LHC. We develop a new fine tuning measure that accurately counts each contribution to fine tuning (single, double, triple, etc) that can occur in a theory with n p parameters, that must reproduce n o observables. We then use a novel scanning procedure to perform a comprehensive study of three different two-site, 4D, SO(5) → SO(4) MCHMs with all third generation fermions included, distinguished by the choice of the lepton embeddings. These are the MCHM 5-5-5 5-5-5 , MCHM 5-5-5 14-14-10 and MCHM 5-5-5 14-1-10 , where MCHM q−t−b l−τ −ν has the lepton doublet partner in representation l, tau partner in representation τ , and so on. We find that embedding at least one massive lepton in the symmetric 14 of SO (5) moderately reduces the tuning for the case of low top partner masses (in line with previous results), but that this is balanced against the increased complexity of the model when one properly accounts for all sources of fine tuning. We study both the current relative fine-tuning of each scenario, and the future prospects. Noting that the different scenarios behave differently with respect to future improvements in collider measurements, we find that the MCHM 5-5-5 14-1-10 enjoys a relatively low increase in fine tuning even for a future lower bound on the top partner masses of 3.4 TeV (or equivalently a maximum Higgs-fermion or Higgs-gluon coupling deviation of 2%).

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“…A different proposal relying on quark seesaw has been made recently (see for instance [23] and references therein); however, in this setup the periodicity of the Goldstone field is disguised and therefore we will stick to CCZW.…”

Section: A Successful Coleman-weinberg Potentialmentioning

confidence: 99%

Goldstone inflation

Croon

Sanz

Setford

2015

J. High Energ. Phys.

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Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones.

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The dynamical composite Higgs

Cited by 38 publications

References 88 publications

Nonperturbative analysis of the spectrum of meson resonances in an ultraviolet-complete composite-Higgs model

Nonperturbative analysis of the spectrum of meson resonances in an ultraviolet-complete composite-Higgs model

Constraining fine tuning in composite Higgs models with partially composite leptons

Goldstone inflation

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