Off-Shell Higgs Probe of Naturalness

We study the off-shell production of the Higgs boson at the LHC to probe Higgs physics at higher energy scales utilizing the process gg → h Ã → ZZ. We focus on the energy scale dependence of the off-shell Higgs propagation, and of the top quark Yukawa coupling, y t ðQ 2 Þ. Extending our recent study [D. Goncalves, T. Han, and S. Mukhopadhyay, Phys. Rev. Lett. 120, 111801 (2018).], we first discuss threshold effects in the Higgs propagator due to the existence of new states, such as a gauge singlet scalar portal, and a possible continuum of states in a conformal limit, both of which would be difficult to discover in other traditional searches. We then examine the modification of y t ðQ 2 Þ from its Standard Model (SM) prediction in terms of the renormalization group running of the top Yukawa, which could be significant in the presence of large flat extra dimensions. Finally, we explore possible strongly coupled new physics in the top-Higgs sector that can lead to the appearance of a nonlocal Q 2 -dependent form factor in the effective top-Higgs vertex. We find that considerable deviations compared to the SM prediction in the invariant mass distribution of the Z-boson pair can be conceivable, and may be probed at the 2σ level at the high-luminosity 14 TeV HL-LHC for a new physics scale up to Oð1 TeVÞ, and at the upgraded 27 TeV HE-LHC for a scale up to Oð3 TeVÞ. For a few favorable scenarios, 5σ level observation may be possible at the HE-LHC for a scale of about Oð1 TeVÞ.

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“…We have discussed such a scenario in a recent study [6]. The scenario can be described by a simple low-energy effective Lagrangian as follows:…”

Section: Virtual Effects From Higgs Portalmentioning

confidence: 99%

“…As a first example, following our recent study [6], a new scalar singlet sector is introduced in the low-energy effective theory that couples to the Higgs field. Such a scalar sector can have implications for the littlehierarchy problem.…”

Section: Introductionmentioning

confidence: 99%

Higgs couplings at high scales

2018

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“…These are difficult to detect when they can be produced only via off-shell Higgs boson decay. It may be possible to detect their existence at the high-luminosity 14 TeV LHC via their one-loop contribution to the process pp → h * → ZZ if the scalar mass is less than around 200 GeV [20]; we anticipate that a similar contribution could arise from heavy clockwork scalars if their mass were not too large compared to the Higgs mass. At future e + e − colliders producing large numbers of Higgs bosons, for example CLIC at 3 TeV, it may be possible to directly produce heavy clockwork scalar pairs via off-shell Higgs decay.…”

Section: Discussionmentioning

confidence: 97%

Clockwork Higgs portal model for freeze-in dark matter

Kim

McDonald

2018

Phys. Rev. D

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The clockwork mechanism can explain interactions which are dimensionally very weak without the need for very large mass scales. We present a model in which the clockwork mechanism generates the very small Higgs portal coupling and dark matter particle mass necessary to explain cold dark matter via the freeze-in mechanism. We introduce a TeV-scale scalar clockwork sector which couples to the Standard Model via the Higgs portal. The dark matter particle is the lightest scalar of the clockwork sector. We show that the freezein mechanism is dominated by decay of the heavy clockwork scalars to light dark matter scalars and Higgs bosons. In the model considered, we find that freeze-in dark matter is consistent with the clockwork mechanism for global charge q in the range 2 ≲ q ≲ 4 when the number of massive scalars is in the range 10 ≤ N ≤ 20. The dark matter scalar mass and portal coupling are independent of q and N. For a typical TeV-scale clockwork sector, the dark matter scalar mass is predicted to be of the order of a MeV.

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“…We propose a new method 1 for measuring Γ t that is linearly sensitive to Γ t . The idea is motivated by recent proposals to measure the Higgs boson width from nonresonant production [16][17][18][19], which has interesting beyond the Standard Model (BSM) sensitivity [20][21][22][23][24][25][26][27] and 1 Similar ideas were recently discussed in Ref. [12][13][14].…”

Section: Introductionmentioning

confidence: 95%

Extracting the Top-Quark Width from Nonresonant Production

2019

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In the context of the Standard Model (SM) of particle physics, the relationship between the topquark mass and width (Γt) has been precisely calculated. However, the uncertainty from current direct measurements of the width is nearly 50%. A new approach for directly measuring the topquark width using events away from the resonance peak is presented. By using an orthogonal dataset to traditional top-quark width extractions, this new method may enable significant improvements in the experimental sensitivity in a method combination. Recasting a recent ATLAS differential cross section measurement, we find Γt = 1.28 ± 0.30 GeV (1.33 ± 0.29 GeV expected), providing the most precise direct measurement of the width.

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Off-Shell Higgs Probe of Naturalness

Cited by 28 publications

References 47 publications

Higgs couplings at high scales

Higgs couplings at high scales

Clockwork Higgs portal model for freeze-in dark matter

Extracting the Top-Quark Width from Nonresonant Production

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