Review on Composite Higgs Models

Witzel, Oliver

doi:10.22323/1.334.0006

Cited by 70 publications

(72 citation statements)

References 72 publications

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“…We therefore present our results for the ten flavor step scaling function in Figs. [3][4][5] showing the nWS analysis on the left and the and WS analysis on the right.…”

Section: A Preferred (N)ws Analysismentioning

confidence: 99%

Gradient flow step-scaling function for SU(3) with twelve flavors

2019

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We calculate the step scaling function, the lattice analog of the renormalization group β-function, for an SU(3) gauge theory with ten fundamental flavors. We present a detailed analysis including the study of systematic effects of our extensive data set generated with ten dynamical flavors using the Symanzik gauge action and three times stout smeared Möbius domain wall fermions. Using up to 32 4 volumes, we calculate renormalized couplings for different gradient flow schemes and determine the step-scaling β function for a scale change s = 2 on up to five different lattice volume pairs. In an accompanying paper we discuss that gradient flow can promote lattice dislocations to instantonlike objects, introducing nonperturbative lattice artifacts to the step scaling function. Motivated by the observation that Wilson flow sufficiently suppresses these artifacts, we choose Wilson flow with the Symanzik operator as our preferred analysis. We study systematic effects by calculating the step-scaling function based on alternative flows (Zeuthen or Symanzik), alternative operators (Wilson plaquette, clover), and also explore the effects of the perturbative tree-level improvement. Further we investigate the effects due to the finite value of Ls. c 11. At that strong coupling we also discovered previously unaccounted lattice artifacts. In an accompanying paper we discuss that gradient flow on coarse configurations can promote dislocations to instanton-like objects. This introduces a nonperturbative lattice artifact to the step scaling beta function which leads to incorrect continuum limit extrapolations [25]. We find that the perturbatively arXiv:2004.00754v1 [hep-lat] 2 Apr 2020 3 The good properties of this action has been first demonstrated for simulations in QCD [42,43] but is now also used in large scale simulations of a composite Higgs model [44][45][46]

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“…We therefore present our results for the ten flavor step scaling function in Figs. [3][4][5] showing the nWS analysis on the left and the and WS analysis on the right.…”

Section: A Preferred (N)ws Analysismentioning

confidence: 99%

Gradient flow step-scaling function for SU(3) with twelve flavors

2019

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“…One could try to look at QCD, (defined here as a SU(3) gauge theory with N f massless Dirac fermions 6 ) for guidance, but even in this much studied case the situation is still unclear. Hoping not to misrepresent or neglect too many of the lattice results, reviewed in [34,35], it seems that the conformal window should start from N f somewhere in the range 8-12 with N f = 8 likely to be outside [36,37] (thus chirally broken and confining). While [38][39][40][41][42][43] find N f = 12 conformal, [44,45] find results compatible with the chirally broken phase.…”

Section: Applications To Partial Compositenessmentioning

confidence: 99%

Anomalous dimensions of potential top-partners

Franzosi

Ferretti

2019

SciPost Phys.

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We discuss anomalous dimensions of top-partner candidates in theories of Partial Compositeness. First, we revisit, confirm and extend the computation by DeGrand and Shamir of anomalous dimensions of fermionic trilinears. We present general results applicable to all matter representations and to composite operators of any allowed spin. We then ask the question of whether it is reasonable to expect some models to have composite operators of sufficiently large anomalous dimension to serve as top-partners. While this question can be answered conclusively only by lattice gauge theory, within perturbation theory we find that such values could well occur for some specific models. In the Appendix we collect a number of practical group theory results for fourth-order invariants of general interest in gauge theories with many irreducible representations of fermions.

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“…In a general composite Higgs model, the mass of the SM fermions is generated through either four-fermion interactions [33] or partial compositeness [18]. The latter presents a need for fermions in (at least) two different irreducible representations of the unbroken hypercolor group G HC , leading to a rich spectrum within the theory [34]. All models considered in this work thus contain two species of underlying fermions which we denote ψ and χ following the notation of Ref.…”

Section: Theoretical Motivationmentioning

confidence: 99%

Future lepton collider prospects for a ubiquitous composite pseudoscalar

et al. 2020

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Composite Higgs models feature new strong dynamics leading to the description of the Higgs boson as a bound state arising from the breaking of a global (flavor) symmetry. These models generally include light states generated by the same dynamics, the detection of which may present the first observable signs of compositeness. One such state is a pseudoscalar boson resulting from the breaking of a Uð1Þ symmetry common to most composite setups, and whose hints are expected to be visible through low-mass resonance searches at present and future hadron and lepton colliders. In this work we study the phenomenology of this pseudoscalar field. We show that, for a light state, bottom quark loop effects dominantly impact the production cross section and considerably modify the decay pattern. Moreover, we make a case for targeted low-mass analyses at future lepton colliders, with an emphasis on high-luminosity machines aiming to operate at low center-of-mass energies. We present a simplified outline of a search for this light pseudoscalar at one such machine, considering electron-positron collisions at the Z-pole. We focus on a signature arising from the pseudoscalar decay into a pair of hadronic taus and a production mode association with a pair of leptons of opposite electric charges, and compare cut and count methods with machine learning methods.

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Review on Composite Higgs Models

Cited by 70 publications

References 72 publications

Gradient flow step-scaling function for SU(3) with twelve flavors

Gradient flow step-scaling function for SU(3) with twelve flavors

Anomalous dimensions of potential top-partners

Future lepton collider prospects for a ubiquitous composite pseudoscalar

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