ORCID Profile
0000-0001-5958-6366
Current Organisation
University of Adelaide
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Publisher: Springer Science and Business Media LLC
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 04-2021
Abstract: The electroweak phase transition can be made first order by extending the Standard Model (SM) Higgs sector with extra scalars. The same new physics can explain the matter-antimatter asymmetry of the universe by supplying an extra source of CP violation and sphaleron processes. In this paper we study the existence of strong first order electroweak phase transition (SFOEWPT) in the type-I and type-II two Higgs doublet models (2HDM). We focus on how the SFOEWPT requirements constraint the spectrum of non-SM Higgs. Through the parameter space scan, we find that SFOEWPT suggests an upper limit on the masses of heavy Higgs $$ {m}_{A/H/{H}^{\pm }} $$ m A / H / H ± , which is around 1 TeV. High temperature expansion and Higgs vacuum uplifting is used for an analytical understanding of our results. After taking into account the probe ability on SFOEWPT from theoretical constraints, Higgs and Z -pole precision measurements up to the one-loop level at future Higgs & Z factories, sizeable loop corrections require $$ {m}_{A/{H}^{\pm }}-{m}_H $$ m A / H ± − m H ∈ (100 , 250) GeV to meet SFOEWPT condition for Type-II 2HDM, and $$ \left|{m}_{A/{H}^{\pm }}-{m}_H\right| $$ m A / H ± − m H ∈ (100 , 350) GeV or $$ \left|{m}_A-{m}_{H/{H}^{\pm }}\right| $$ m A − m H / H ± ∈ (100 , 350) GeV for Type-I 2HDM.
Publisher: Springer Science and Business Media LLC
Date: 03-2019
Abstract: Future precision measurements of the Standard Model (SM) parameters at the proposed Z -factories and Higgs factories may have significant impacts on new physics beyond the Standard Model in the electroweak sector. We illustrate this by focusing on the Type-II two Higgs doublet model (Type-II 2HDM). The contributions from the heavy Higgs bosons at the tree-level and at the one-loop level are included in a full model parameter space. We perform a multiple variable global fit and study the extent to which the parameters of non-alignment and non-degenerate masses can be probed by the precision measurements. We find that the allowed parameter ranges are tightly constrained by the future Higgs precision measurements, especially for small and large values of tan β . Indirect limits on the masses of heavy Higgs can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the Z -pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are | cos( β − α )| 0 . 008 , |Δ m Φ | 200 GeV, and tan β ∼ 0 . 2 − 5. The reaches from CEPC, FCC-ee and ILC are also compared, for both Higgs and Z -pole precision measurements.
Publisher: Springer Science and Business Media LLC
Date: 05-2021
Abstract: Models in which the Higgs boson is a composite pseudo-Nambu-Goldstone boson offer attractive solutions to the Higgs mass naturalness problem. We consider three such models based on the minimal SO (5) → SO (4) symmetry breaking pattern, and perform convergent global fits on the models under a Bayesian framework in order to find the regions of their parameter spaces that best fit a wide range of constraints, including recent Higgs measurements. We use a novel technique to analyse the fine-tuning of the models, quantifying the tuning as the Kullback-Leibler ergence from the prior to the posterior probability on the parameter space. Each model is found to be able to satisfy all constraints at the 3 σ level simultaneously. As a by-product of the fits, we analyse the collider phenomenology of our models in these viable regions. In two of the three models, we find that the gg → H → γγ cross section is less than ∼90% that predicted by the SM, which is already in slight tension with experiment and could potentially be ruled out in the future high-luminosity run of the LHC. In addition, the lightest fermions F arising from the new strong dynamics in these models are seen in general to lie above ∼1 . 1 TeV, with the F → tW + and F → $$ \\overline{b}{W}^{+} $$ b ¯ W + decays offering particularly promising channels for probing these models in future collider searches.
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Abstract: We explore the extent to which future precision measurements of the Standard Model (SM) observables at the proposed Z -factories and Higgs factories may have impacts on new physics beyond the Standard Model, as illustrated by studying the Type-I Two-Higgs-doublet model (Type-I 2HDM). We include the contributions from the heavy Higgs bosons at the tree-level and at the one-loop level in a full model-parameter space. While only small tan β region is strongly constrained at tree level, the large tan β region gets constrained at loop level due to tan β enhanced tri-Higgs couplings. We perform a multiple variable χ 2 fit with non-alignment and non-degenerate masses. We find that the allowed parameter ranges could be tightly constrained by the future Higgs precision measurements, especially for small and large values of tan β . Indirect limits on the masses of heavy Higgs bosons can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the Z -pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are | cos( β − α ) | 0 . 05 , | ∆ m Φ | 200 GeV, and tan β ≳ 0 . 3. The reaches from CEPC, Fcc-ee and ILC are also compared, for both Higgs and Z -pole precision measurements. Comparing to the Type-II 2HDM, the 95% C.L. allowed range of cos( β − α ) is larger, especially for large values of tan β .
Publisher: Springer Science and Business Media LLC
Date: 02-2021
Abstract: The Higgs sector in neutral naturalness models provides a portal to the hidden sectors, and thus measurements of Higgs couplings at current and future colliders play a central role in constraining the parameter space of the model. We investigate a class of neutral naturalness models, in which the Higgs boson is a pseudo-Goldstone boson from the universal SO( N ) / SO( N − 1) coset structure. Integrating out the radial mode from the spontaneous global symmetry breaking, we obtain various dimension-six operators in the Standard Model effective field theory, and calculate the low energy Higgs effective potential with radiative corrections included. We perform a χ 2 fit to the Higgs coupling precision measurements at current and future colliders and show that the new physics scale could be explored up to 2.3 (2.4) TeV without (with) the Higgs invisible decay channels at future Higgs factories. The limits are comparable to the indirect constraints obtained via electroweak precision measurements.
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