What the Oblique Parameters S, T and U and Their Extensions Reveal About the 2hdm: A Numerical Analysis

Funk, Gerhardt; O’Neil, Deva; Winters, R. Michael

doi:10.1142/s0217751x12500212

Cited by 39 publications

(27 citation statements)

References 15 publications

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“…In 2HDMs there is a strong correlation between T and U , and T is the most sensitive of the three oblique parameters. Thus, U is much smaller in points not excluded by an extremely large value of T [87], and the contributions to U can safely be dropped. Therefore, for points to be in agreement with the experimental observation, we require that the prediction of the S and the T parameter are within the 2 σ ellipse, corresponding to χ 2 = 5.99 for two degrees of freedom.…”

Section: Constraints From Electroweak Precision Datamentioning

confidence: 99%

A 96 GeV Higgs boson in the N2HDM

2020

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We discuss a ∼ 3 σ signal (local) in the light Higgs-boson search in the diphoton decay mode at ∼ 96 GeV as reported by CMS, together with a ∼ 2 σ excess (local) in the bb final state at LEP in the same mass range. We interpret this possible signal as a Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We find that the lightest Higgs boson of the N2HDM can perfectly fit both excesses simultaneously, while the second lightest state is in full agreement with the Higgs-boson measurements at 125 GeV, and the full Higgs-boson sector is in agreement with all Higgs exclusion bounds from LEP, the Tevatron and the LHC as well as other theoretical and experimental constraints. We show that only the N2HDM type II and IV can fit both the LEP excess and the CMS excess with a large ggF production component at ∼ 96 GeV. We derive bounds on the N2HDM Higgs sector from a fit to both excesses and describe how this signal can be further analyzed at the LHC and at future e + e − colliders, such as the ILC.SM is the Minimal Supersymmetric Standard Model (MSSM) [19,20]. In contrast to the single Higgs doublet of the SM, the MSSM by construction, requires the presence of two Higgs doublets, Φ 1 and Φ 2 . In the CP conserving case the MSSM Higgs sector consists of two CP-even, one CP-odd and two charged Higgs bosons. The light (or the heavy) CP-even MSSM Higgs boson can be interpreted as the signal discovered at ∼ 125 GeV [21] (see Refs. [22,23] for recent updates). However, in Ref. [22] it was demonstrated that the MSSM cannot explain the CMS excess in the diphoton final state.Going beyond the MSSM, a well-motivated extension is given by the Next-to-MSSM (NMSSM) (see [24,25] for reviews). The NMSSM provides a solution for the so-called "µ problem" by naturally associating an adequate scale to the µ parameter appearing in the MSSM superpotential [26,27]. In the NMSSM a new singlet superfield is introduced, which only couples to the Higgs-and sfermion-sectors, giving rise to an effective µ-term, proportional to the vacuum expectation value (vev) of the scalar singlet. In the CP conserving case the NMSSM Higgs sector consists of three CP-even Higgs bosons, h i (i = 1, 2, 3), two CP-odd Higgs bosons, a j (j = 1, 2), and the charged Higgs boson pair H ± . In the NMSSM not only the lightest but also the second lightest CP-even Higgs boson can be interpreted as the signal observed at about 125 GeV, see, e.g., [28,29]. In Ref. [17] it was found that the NMSSM can indeed simultaeneously satisfy the two excesses mentioned above. In this case, the Higgs boson at ∼ 96 GeV has a large singlet component, but also a sufficiently large doublet component to give rise to the two excesses.A natural extension of the NMSSM is the µνSSM, in which the singlet superfield is interpreted as a right-handed neutrino superfield [30,31] (see for reviews). The µνSSM is the simplest extension of the MSSM that can provide massive neutrinos through a see-saw mechanism at the electroweak scale. A Yukawa coupling for right-handed ne...

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Section: Constraints From Electroweak Precision Datamentioning

confidence: 99%

A 96 GeV Higgs boson in the N2HDM

2020

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“…The oblique parameters S, T and U provide important constrains from electroweak precisiton data on many models beyond the SM. These parameters have been calculated at the one loop in the two Higgs doublet model [82][83][84]. We focus on the scenario where wH, A and H + With this assumption, we scan for the predicted values of S and T as a function of the mixing angle sin(α − β).…”

Section: Electroweak Precision Constraints Boundedness and Unitaritymentioning

confidence: 99%

Enhanced di-Higgs production in the two Higgs doublet model

Babu

Jana

2019

J. High Energ. Phys.

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We show that the rate for di-Higgs production at the LHC can be enhanced by a factor as large as 25 compared to the Standard Model value in the two Higgs doublet model, while being consistent with the known properties of the observed Higgs boson h. There are correlated modifications in tth and resonant Zh production rates, which can serve as tests of this model. Our framework treats both Higgs doublets on equal footing, each with comparable Yukawa couplings to fermions. The Cheng-Sher ansatz for multi-Higgs doublet model is shown to be strongly disfavored by current experiments. We propose a new ansatz for the Yukawa couplings of the Higgs doublets Φ a is proposed, where Y In the 2HDM framework that we adopt there is no fundamental distinction between the two Higgs doublets. The top quark, bottom quark and tau lepton Yukawa couplingsmost relevant for LHC phenomenology -with both doublets are then comparable, unlike in the case of type-I or type-II 2HDM. We shall see that these additional couplings, especially of the top and bottom quarks, would lead to distinct signatures in the hh, tth and Zh production rates in a correlated manner. Here h is the standard model-like Higgs boson of mass 125 GeV. While there would be some deviations in the properties of h from the SM predictions, in our analysis we ensure that such deviations are within experimental limits. Modifications in hh, tth and Zh production rates will also be correlated with such deviations in the properties of h. Discovery of these correlated modifications would be tests of the model.tth production: Theoretically, tth production process is very interesting, as its rate is proportional to Y 2 t , the square of the top Yukawa coupling with the Higgs boson. Within the SM, Y t is known to a good accuracy, as it is related to the top quark mass. But this proportionality relation is disrupted in the 2HDM we present. In Run−I of the LHC, a not-

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“…For example, the oblique S, T and U parameters [43] receive contributions S, T and U , respectively, from the 2HDM [44]. The most constraining amongst these is T , which reads [45,46] …”

Section: Oblique Parameters and Flavour Constraintsmentioning

confidence: 99%

High-scale validity of a two-Higgs-doublet scenario: metastability included

Chakrabarty

Mukhopadhyaya

2017

Eur. Phys. J. C

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We identify regions in a Type-II two-Higgsdoublet model which correspond to a metastable electroweak vacuum with lifetime larger than the age of the universe. We analyse scenarios which retain perturbative unitarity up to grand unification and Planck scales. Each point in the parameter space is restricted using data from the Large Hadron Collider (LHC) as well as flavour and precision electroweak constraints. We find that substantial regions of the parameter space are thus identified as corresponding to metastability, which complement the allowed regions for absolute stability, for top quark mass at the high as well as low end of its currently allowed range. Thus, a two-Higgs-doublet scenario with the electroweak vacuum, either stable or metastable, can sail through all the way up to the Planck scale without facing any contradiction.

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What the Oblique Parameters S, T and U and Their Extensions Reveal About the 2hdm: A Numerical Analysis

Cited by 39 publications

References 15 publications

A 96 GeV Higgs boson in the N2HDM

A 96 GeV Higgs boson in the N2HDM

Enhanced di-Higgs production in the two Higgs doublet model

High-scale validity of a two-Higgs-doublet scenario: metastability included

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