On the exotic Higgs decays in effective field theory

Bélusca-Maïto, Hermès; Falkowski, Adam

doi:10.1140/epjc/s10052-016-4362-8

Cited by 19 publications

(26 citation statements)

References 96 publications

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“…The existing experimental results suggest that | tan β| < ∼ 0.3, if h 0 is to mimic the SM Higgs boson (see e.g. [14]). Since there are two scalars in this model, two equations (5) must be simultaneously satisfied [15].…”

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confidence: 99%

Softly broken conformal symmetry and the stability of the electroweak scale

et al. 2015

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We point out a novel possible mechanism by which the electroweak hierarchy problem can be avoided in the (effective) quantum field theory. Assuming the existence of a UV complete underlying fundamental theory and treating the cutoff scale Λ of the effective field theory as a real physical scale we argue that the hierarchy problem would be solved if the coefficient in front of quadratic divergences vanished for some choice of Λ, and if the effective theory mass parameters fixed at Λ by the fundamental theory were hierarchically smaller than Λ itself. While this mechanism most probably cannot work in the Standard Model if the scale Λ is to be close to the Planck scale, we show that it can work in a minimal extension (Conformal Standard Model) proposed recently for a different implementation of soft conformal symmetry breaking.PACS numbers: 12.60. Fr,1480.Ec,14.80Va The problem of stability of the electroweak scale with respect to the Planck scale (the so-called hierarchy problem) has for almost 40 years been one of the main driving forces of theoretical research in high energy physics. Over the years various mechanisms for solving it at the effective quantum field theory level have been proposed and investigated in detail, of which the most notable are technicolor and low energy supersymmetry. With the discovery of a spin-zero particle at the LHC, and after establishing its basic characteristics, it has become clear that a solution which departs little from the simplest mechanism of the electroweak symmetry breaking realized in the Standard Model (SM) may be preferred. In particular, extensions of the SM which predict only elementary scalars and no new higher spin particles other than right-chiral neutrinos seem distinguished at present. It is therefore of interest that there exists an alternative way (which does not require new spin s ≥ 1 2 degrees of freedom) by which the problem of stability of the electroweak scale could be avoided in the low energy effective theory. It is based on a novel implementation of 'near conformal symmetry' in the effective low energy theory.As is well known, the classical conformal symmetry of the SM is spoiled only by the scalar field mass term necessary to induce phenomenologically viable electroweak symmetry breaking. Moreover, as in any generic quantum field theory, conformal symmetry of the SM is broken by quantum effects. Yet, the idea that 'softly broken conformal symmetry' (SBCS) might be relevant for the solution of the hierarchy problem was expressed already long ago [1]. As one possible concrete implementation of this idea a minimal extension of the SM, the Conformal Standard Model (CSM), has been proposed in [2]. Besides the known particles this model only involves the right-chiral neutrinos and one extra (complex) scalar field. Originally it was assumed that its conformal symmetry is broken only by the anomaly, inducing electroweak symmetry breaking via the Coleman-Weinberg mechanism [3]. However, although there do exist perturbatively stable minima of the potential o...

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confidence: 99%

Softly broken conformal symmetry and the stability of the electroweak scale

et al. 2015

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“…We allow for different values for thec H W parameter and we present, in the lower panels, the bin-by-bin ratio of the new physics predictions to the Standard Model expectation which now depends on the Wilson coefficients and on the M cut T minimum value for the transverse mass, as well as an asymmetry as in Eq. (29),…”

Section: H Higgs and Weak-boson Associated Productionmentioning

confidence: 99%

“…As far as gauge interactions are concerned, CPV effects can be parameterized by six independent dimensions-six operators yielding novel interactions involving at least either three gauge and Higgs bosons, or gauge bosons only. The magnitude of the corresponding Wilson coefficients is in general constrained by electric dipole moments data and electroweak precision tests [16,[22][23][24], as well as by fits of Higgs coupling measurements at the LHC [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Probing $$\textit{CP}$$-violating Higgs and gauge-boson couplings in the Standard Model effective field theory

et al. 2017

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We study the phenomenological consequences of several C P-violating structures that could arise in the Standard Model effective field theory framework. Focusing on operators involving electroweak gauge and/or Higgs bosons, we derive constraints originating from Run I LHC data. We then study the capabilities of the present and future LHC runs at higher energies to further probe associated C P-violating phenomena and we demonstrate how differential information can play a key role. We consider both traditional four-lepton probes of C P-violation in the Higgs sector and novel new physics handles based on varied angular and non-angular observables.

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“…The fact that the observed boson has features which, at least in the broad brush, match with the SM expectations confirms that it is the principle agent of electroweak symmetry breaking. A major focus of the LHC run II is to establish its properties to high precision to either confirm the SM vision for electroweak breaking or to find the influence of new physics [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%