The Higgs: so simple yet so unnatural

Altarelli, Guido

doi:10.1051/epjconf/20147100005

Cited by 10 publications

(9 citation statements)

References 38 publications

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“…The SM Higgs sector is famously unnatural [49,50]. In particular, a fine tuning of the Higgs sector squared-mass parameter is required in order to explain the observed value of the vacuum expectation value (vev), v ≈ 246 GeV.…”

Section: Higgs Couplings and The Alignment Limitmentioning

confidence: 99%

Scrutinizing the alignment limit in two-Higgs-doublet models:mh=125 GeV

Bernon

Gunion

Haber³

et al. 2015

Phys. Rev. D

194

181

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In the alignment limit of a multi-doublet Higgs sector, one of the Higgs mass eigenstates aligns with the direction of the scalar field vacuum expectation values, and its couplings approach those of the Standard Model (SM) Higgs boson. We consider CP-conserving Two-Higgs-Doublet Models (2HDMs) of Type I and Type II near the alignment limit in which the lighter of the two CP-even Higgs bosons, h, is the SM-like state observed at 125 GeV. In particular, we focus on the 2HDM parameter regime where the coupling of h to gauge bosons approaches that of the SM. We review the theoretical structure and analyze the phenomenological implications of the regime of alignment limit without decoupling, in which the other Higgs scalar masses are not significantly larger than m h and thus do not decouple from the effective theory at the electroweak scale. For the numerical analysis, we perform scans of the 2HDM parameter space employing the software packages 2HDMC and Lilith, taking into account all relevant pre-LHC constraints, the latest constraints from the measurements of the 125 GeV Higgs signal at the LHC, as well as the most recent limits coming from searches for heavy Higgs-like states. We contrast these results with the alignment limit achieved via the decoupling of heavier scalar states, where h is the only light Higgs scalar. Implications for Run 2 at the LHC, including expectations for observing the other scalar states, are also discussed. *

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Section: Higgs Couplings and The Alignment Limitmentioning

confidence: 99%

Scrutinizing the alignment limit in two-Higgs-doublet models:mh=125 GeV

Bernon

Gunion

Haber³

et al. 2015

Phys. Rev. D

194

181

View full text Add to dashboard Cite

show abstract

“…[18][19][20]. [25][26][27][28][29][30][31][32] also adopt weak scale fine-tuning for their discussion. Ref.…”

Section: Jhep06(2014)172mentioning

confidence: 99%

Physics at a Higgsino factory

Baer

Barger

Mickelson

et al. 2014

J. High Energ. Phys.

108

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Naturalness arguments applied to supersymmetric theories imply a spectrum containing four light higgsinos Z 1,2 and W ± 1 with masses ∼ 100 − 300 GeV (the closer to M Z , the more natural). The compressed mass spectrum and associated low energy release from W 1 and Z 2 three-body decay makes higgsinos difficult to detect at LHC14, while the other sparticles might be heavy, and possibly even beyond LHC14 reach. In contrast, the International Linear e + e − Collider (ILC) with √ s > 2m(higgsino) would be a higgsino factory in addition to a Higgs boson factory and would serve as a discovery machine for natural SUSY! In this case, both chargino and neutralino production occur at comparable rates, and lead to observable signals above SM backgrounds. We examine two benchmark cases, one just beyond the LHC8 reach with W 1 ( Z 2 ) − Z 1 mass gap of 15 (21) GeV, and a second more difficult case beyond even the LHC14 reach, where the mass gap is just 10 GeV, close to its minimum in models with no worse than 3% finetuning. The signal is characterized by low visible energy events together with E T in the one or two jets +1ℓ channel from chargino production, and in the opposite sign, sameflavour, acoplanar dilepton channel from Z 1 Z 2 production. For both cases, we find that the signal is observable above backgrounds from the usual 2 → 2 SM events and from γγ collisions with just a few fb −1 of integrated luminosity. We also show that with an integrated luminosity of 100 fb −1 , it should be possible to extract W 1 and Z 1 masses at 2-3% level from chargino events if the mass gap is ≥ 15 GeV, and neutralino masses at the sub-percent level from neutralino events. The latter should also allow a determination of m Z 2 − m Z 1 at the 200 MeV level. These measurements would point to higgsinos as the origin of new physics and strongly suggest a link to a natural origin for W , Z and h masses.

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“…It is well possible that dark matter (DM) consists of particles which emerge from some grand unified theory (GUT) and are stable due to a remnant discrete symmetry. The recent revival of non-supersymmetric GUTs [2][3][4][5][6][7][8][9] motivates us to study dark matter candidates in a non-supersymmetric GUT with gauge group E 6 . The exceptional rank-6 group E 6 has one important advantage over the widely studied SU(5) [10] and SO(10) [11] groups when it comes to dark matter: the fundamental representation of E 6 contains, in addition to the standard model fermions, several exotic fermions.…”

Section: Introductionmentioning

confidence: 99%

Dark matter in E6 Grand unification

Schwichtenberg

2018

J. High Energ. Phys.

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We discuss fermionic dark matter in non-supersymmetric E 6 Grand Unification. The fundamental representation of E 6 contains, in addition to the standard model fermions, exotic fermions and we argue that one of them is a viable, interesting dark matter candidate. Its stability is guaranteed by a discrete remnant symmetry, which is an unbroken subgroup of the E 6 gauge symmetry. We compute the symmetry breaking scales and the effect of possible threshold corrections by solving the renormalization group equations numerically after imposing gauge coupling unification. Since the Yukawa couplings of the exotic and the standard model fermions have a common origin, the mass of the dark matter particles is constrained. We find a mass range of 3 · 10 9 GeV m DM 1 · 10 13 GeV for our E 6 dark matter candidate, which is within the reach of next-generation direct detection experiments.

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The Higgs: so simple yet so unnatural

Cited by 10 publications

References 38 publications

Scrutinizing the alignment limit in two-Higgs-doublet models:mh=125 GeV

Scrutinizing the alignment limit in two-Higgs-doublet models:mh=125 GeV

Physics at a Higgsino factory

Dark matter in E6 Grand unification

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