Implications of vector boson scattering unitarity in composite Higgs models

Franzosi, Diogo Buarque; Ferrarese, Piero

doi:10.1103/physrevd.96.055037

Cited by 10 publications

(11 citation statements)

References 125 publications

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“…This requirement is connected to the one above, as we expect that the σ plays a crucial role in taming the growth with energy of the amplitude, like in QCD [50]. We will base our estimate on the leading order calculation, even though radiative corrections typically tend to increase the amplitude and push the resonance mass to lower values [47]. Neglecting effects from the potential, which are irrelevant at high energies, the asymptotic behaviour of the pNGB scattering in the sigma channel (projection on zero isospin and angular momentum,…”

Section: Perturbativity and Unitaritymentioning

confidence: 92%

Sigma-assisted low scale composite Goldstone–Higgs

2020

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We show that the presence of a lightish scalar resonance, σ , that mixes with the composite Goldstone-Higgs boson can relax the typical bounds found in this class of models. This mechanism, inbred in models with a walking dynamics above the condensation scale, allows for a low compositeness scale f 400 GeV, corresponding to a misalignment angle s θ 0.6, contrary to the common lore of a smaller angle. According to recent lattice results, the light σ emerges thanks to a near-conformal phase above the condensation scale, consistent to the requirements from flavour physics. We study this effect in a general way, showing that it appears in all cosets emerging from an underlying gauge-fermion dynamics, in the presence of top partial compositeness. The scenario is testable both on the Lattice and experimentally, as it requires the presence of a second broad Higgs-like resonance, below 1 TeV, that can be revealed at the LHC in the Z Z and tt channels.

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Section: Perturbativity and Unitaritymentioning

confidence: 92%

Sigma-assisted low scale composite Goldstone–Higgs

2020

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“…The predominant focus of previous work was therefore devoted to isolating the resonance shape and cross section, which is not our focus here. Note, however, that loop effects and their relation to (Higgs) effective field theory were first discussed in [81][82][83][84].…”

Section: A Simplified Model and Its Eft Limitmentioning

confidence: 99%

Effective field theory and scalar extensions of the top quark sector

2020

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Effective field theory (EFT) approaches are widely used at the LHC, such that it is important to study their validity, and ease of matching to specific new physics models. In this paper, we consider a generic extension of the SM in which a top quark couples to a new heavy scalar. We find the dimension six operators generated by this theory at low energy, and match the EFT to the full theory up to NLO precision in the simplified model coupling. We then examine the range of validity of the EFT description in top pair production, finding excellent validity even if the scalar mass is only slightly above LHC energies, provided NLO corrections are included. In the absence of the latter, the LO EFT overestimates kinematic distributions, such that over-optimistic constraints on BSM contributions are obtained. We next examine the constraints on the EFT and full models that are expected to be obtained from both top pair and four top production at the LHC, finding for low scalar masses that both processes show similar exclusion power. However, for larger masses, estimated LHC uncertainties push constraints into the non-perturbative regime, where the full model is difficult to analyse, and thus not perturbatively matchable to the EFT. This highlights the necessity to improve uncertainties of SM hypotheses in top final states.

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“…In the following sections we will use these benchmark points to predict the visibility of vector resonances that may exist in the IJ = 11 channel, and therefore resonate in the process W Z → W Z at the LHC. For the IJ = 00 channel there are recent alternative studies of the IAM scalar resonances and their production at the LHC, see for instance [46].…”

Section: Tt Ll Tt Tt Tt Lt Lt Ll Lt Tt Lt Ltmentioning

confidence: 99%

Production of vector resonances at the LHC via WZ-scattering: a unitarized EChL analysis

Delgado

Dobado

Espriu

et al. 2017

J. High Energ. Phys.

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Abstract:In the present work we study the production of vector resonances at the LHC by means of the vector boson scattering W Z → W Z and explore the sensitivities to these resonances for the expected future LHC luminosities. We are assuming that these vector resonances are generated dynamically from the self interactions of the longitudinal gauge bosons, W L and Z L , and work under the framework of the electroweak chiral Lagrangian to describe in a model independent way the supposedly strong dynamics of these modes. The properties of the vector resonances, mass, width and couplings to the W and Z gauge bosons are derived from the inverse amplitude method approach. We implement all these features into a single model, the IAM-MC, adapted for MonteCarlo, built in a Lagrangian language in terms of the electroweak chiral Lagrangian and a chiral Lagrangian for the vector resonances, which mimics the resonant behavior of the IAM and provides unitary amplitudes. The model has been implemented in MadGraph, allowing us to perform a realistic study of the signal versus background events at the LHC. In particular, we have focused our study on the pp → W Zjj type of events, discussing first on the potential of the hadronic and semileptonic channels of the final W Z, and next exploring in more detail the most clear signals. These are provided by the leptonic decays of the gauge bosons, leading to a final state with + 1 − 1 + 2 νjj, = e, µ, having a very distinctive signature, and showing clearly the emergence of the resonances with masses in the range of 1.5-2.5 TeV, which we have explored.

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Implications of vector boson scattering unitarity in composite Higgs models

Cited by 10 publications

References 125 publications

Sigma-assisted low scale composite Goldstone–Higgs

Sigma-assisted low scale composite Goldstone–Higgs

Effective field theory and scalar extensions of the top quark sector

Production of vector resonances at the LHC via WZ-scattering: a unitarized EChL analysis

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