Fitting the $Z b \bar b$ vertex in the two-Higgs-doublet model and in the three-Higgs-doublet model
Darius Jurčiukonis, Luis Lavoura
备注：
30 pages, 13 figures; v2: added two footnotes and two references; v3: modified 4 figures and added 3 new figures, all sections have changes, added new appendix and added references; v4 matches published version
We investigate the new contributions to the parameters $g_L$ and $g_R$ of the $Z b \bar b$ vertex in a multi-Higgs-doublet model (MHDM). We emphasize that those contributions generally worsen the fit of those parameters to the experimental data. We propose a solution to this problem, wherein $g_R$ has the opposite sign from the one predicted by the Standard Model; this solution, though, necessitates light scalars and large Yukawa couplings in the MHDM.
In this paper we calculate the one loop contributions to the CP violating three gauge boson couplings in two-Higgs doublet and Left--Right symmetric models. In the two-Higgs doublet model only a P conserving and CP violating coupling is generated, and it can be large as $10^{-3}$. In the Left--Right symmetric model both P conserving and violating couplings are generated. Due to constraints on the $W_L$--$W_R$ mixing, these couplings are small.
We study the one-loop corrections to the $Zb\bar{b}$ vertex in extensions of the Standard Model with arbitrary numbers of scalar doublets, neutral scalar singlets, and charged scalar singlets. Starting with a general parameterization of theories with neutral and singly-charged scalar particles, we derive the conditions that, in a renormalizable model, must be obeyed by the couplings in order for the divergent contributions to cancel. Then, we show that those conditions are indeed obeyed by the models that we are interested in, and we write down the full finite expression for the vertex in thos…
Constraints on the whole spectrum of lepton flavor violating vertices are shown in the context of the standard two Higgs doublet model. The vertex involving the $e-τ$ mixing is much more constrained than the others, and the decays proportional to such vertex are usually very suppressed.
An $H^+ W^- Z$ vertex, i.e, the interaction connecting a singly charged physical scalar to the $W^\pm,~Z$ gauge bosons is absent at the tree level in a scalar sector comprising only $SU(2)_L$ doublets. However, the interaction can be generated radiatively in such a case, an example of which is a two-Higgs doublet model. In this study, we extend a two-Higgs doublet scenario by additional $SU(2)_L$ scalar doublets. Upon endowing with appropriate discrete symmetries, these additional doublets so introduced can furnish successful candidates of dark matter. Interestingly, the same "dark" scalars ca…
Constraints on the whole spectrum of lepton flavor violating vertices are shown in the context of the standard two Higgs doublet model. The vertex involving the $e-τ$ mixing is much more constrained than the others, and the decays proportional to such vertex are usually very supressed. On the other hand, bounds on the quark sector are obtained from leptonic decays of the $B_{d,s}^{0}$ mesons and from $ΔM_{B_{d}^{0}}$. We emphasize that although the $B_{d}^{0}-\bar{B}_{d}^{0}$ mixing restricts severely the $% d-b$ mixing vertex, the upper bound for this vertex could still give a sizeable contri…
The non-decoupling effects of heavy Higgs bosons as well as fermions on the loop-induced $H^\pm W^\mp Z^0$ vertex are discussed in the general two Higgs doublet model. The decay width of the process $H^+ \to W^+ Z^0$ is calculated at one-loop level and the possibility of its enhancement is explored both analytically and numerically. We find that the novel enhancement of the decay width can be realized by the Higgs non-decoupling effects with large mass-splitting between the charged Higgs boson and the CP-odd one. This is due to the large breakdown of the custodial $SU(2)_V$ invariance in the H…
We present global fits to the Two-Higgs-Doublet model, assuming a softly broken $Z_2$ symmetry of the types I and II and CP conservation in the scalar potential. We show how much the parameter space is constrained by the combination of the relevant theoretical and experimental inputs, including the LHC data after the first run and interpreting the 125 GeV boson as the light CP even Higgs. Using the next-to-leading order renormalization group equations, we address the questions of vacuum stability and the hierarchy problem in the context of the mentioned Two-Higgs-Doublet models.
We compute one-loop induced trilinear vertices with physical charged Higgs bosons $H^\pm$ and ordinary gauge bosons, i.e., $H^\pm W^\mp Z$ and $H^\pm W^\mp γ$, in the model with two active plus one inert scalar doublet fields under a $Z_2(\text{unbroken})\times \tilde{Z}_2(\text{softly-broken})$ symmetry. The $Z_2$ and $\tilde{Z}_2$ symmetries are introduced to guarantee the stability of a dark matter candidate and to forbid the flavour changing neutral current at the tree level, respectively. The dominant form factor $F_Z$ of the $H^\pm W^\mp Z$ vertex can be enhanced by non-decoupling effect…
We present the current status of the Two-Higgs-Doublet model of type II. Taking into account all available relevant information, we exclude at $95$% CL sizeable deviations of the so-called alignment limit, in which all couplings of the light CP-even Higgs boson $h$ are Standard-Model-like. While we can set a lower limit of $240$ GeV on the mass of the pseudoscalar Higgs boson at $95$% CL, the mass of the heavy CP-even Higgs boson $H$ can be even lighter than $200$ GeV. The strong constraints on the model parameters also set limits on the triple Higgs couplings: the $hhh$ coupling in the Two-Hi…
In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We extend the Standard Model with two extra Higgs doublets as well as a spontaneously broken $U_X(1)$ gauge symmetry. All the fermion Yukawa couplings except that of top quark are of order ${\cal O} (10^{-2})$ in our model. Constraints on the parameter space from Electroweak precision measurements are studied. Besides, the neutral component of the new fields, which are introduced to…
We study the CP violating ZZZ vertex in the two-Higgs doublet model, which is a probe of a Jarlskog-type invariant in the extended Higgs sector. The form factor $f_4^Z$ is evaluated at one loop in a general $R_ξ$ gauge and its magnitude is estimated in the realistic parameter space. Then we turn to the decoupling limit of the two-Higgs doublet model, where the extra scalars are heavy and the physics can be described by the Standard Model supplemented by higher-dimensional operators. The leading operator contributing to $f_4^Z$ at one loop is identified. The CP violating ZZZ vertex is not gener…
We study the effect of one universal extra dimension on the branching ratios of the lepton flavor violating processes μ\to eγand τ\to μγin the general two Higgs doublet model. We observe that these new effects are tiny for the small values of the compactification radius R. Furthermore, we see that these effects are comparable with the branching ratio obtained without including extra dimension, if the neutral Higgs bosons are nearly degenerate and the complexity of the Yukawa coupling, inducing the vertex tau-tau-$h^0 (A^0)$, is large.
We discuss the realization of two Higgs doublets model in the framework of 6 dimensional Gauge-Higgs Unification model with a simple Lie group G_M. Two Higgs SU(2)_L doublets can emerge at the low energy effective theory, and the quartic coupling terms in the scalar potential, essential for the electroweak symmetry breaking, are now G_M gauge invariant and permissive. A realistic two Higgs doublets model can possibly be obtained only when two of the root vectors associated with the would-be Higgs doublets and the root vector for SU(2)_L form an isosceles triangle with vertex angle either of Pi…
New physics interactions can affect the strength and structure of the $tbW$ vertex. We investigate the magnitudes and phases of "anomalous" contributions to this vertex in a two-Higgs doublet and the minimal supersymmetric extension of the standard model, and in a top-color assisted technicolor (TC2) model. While the magnitudes of the anomalous couplings remain below 1 percent in the first two models, TC2 interactions can reduce the left-chiral coupling $f_L$ by several percent.
Color-octet scalars arise in various Grand Unification scenarios and also in other models of new physics. They are also postulated for minimal flavour violation. Purely phenomenological imprints of such scalars are therefore worth looking at. Motivated by this, we perform a complete one-loop calculation of the $H^+ \to W^+ Z (\g)$ decay in a two Higgs doublet model augmented by a color-octet $SU(2)_L$ scalar doublet. The computation is conveniently segregated into colorless and colored components. The color-octet part of the amplitude, being scaled by the color-factor, provides an overall enha…
We perform a combined analysis of two stringent constraints on two Higgs doublet model, coming from the recently announced CLEO II bound on $B(b \rightarrow s γ)$ and $Z \rightarrow b \overline b$ and from the recent LEP data on the ratio $Γ(Z\rightarrow b\overline b)\over{Γ(Z\rightarrow hadrons)}$. We include one-loop vertex corrections to $Z \rightarrow b \overline b$ in the model. We find that although the CLEO II bound serves as the strongest constraint present in the charged Higgs sector of the model, the current LEP value for $R_b$ may also provide a further constraint for $\tanβ<1$.
A phenomenological analysis of the general two Higgs doublet model is presented. Possible constraints of the Yukawa couplings are obtained from the $K^0-\bar{K}^0, B^0-\bar{B}^0$ and $D^0-\bar{D}^0$ mixings. A much larger $D^0-\bar{D}^0$ mixing than the standard model prediction is possible. It is shown that the emerging of various new sources of CP violation in the model could strongly affect the determination of the unitarity triangle. It can be helpful to look for a signal of new physics by comparing the extracted angle $β$ from two different ways, such as from the process $B\to J/ψK_{S}$ a…
We investigate the effects of the new scalars in a two-Higgs-doublet model on the weak magnetic dipole moments of the fermions at the $Z$ peak. Proportionality of the Yukawa couplings to the fermion masses, and to $\tanβ$, makes such effects more important for the third family, and potentially relevant. For the $τ$ lepton, the new diagrams are suppressed by $v_τ= 2 \sin^2 θ_W - 1/2$, or by powers of $m_τ/M_Z$, but may still be comparable to the SM electroweak contributions. In contrast, we find that the new contributions for the bottom quark may be much larger than the SM electroweak contribut…
I stress the fact that a complete study of possible New Physics effects in the $Z \rightarrow b\bar{b}$ vertex requires a combined analysis of the ratio $R_b= Γ(Z \rightarrow b\bar{b})/ Γ(Z \rightarrow hadrons)$ and the longitudinally polarized forward backward asymmetry, $A_b$. This is illustrated with a number of models such as the two Higgs-doublet model, the MSSM, Technicolour and models with an extra $Z'$. The use of effective lagrangean techniques is briefly discussed.
We perform a combined analysis of two stringent constraints on the 2 Higgs doublet model, one coming from the recently announced CLEO II bound on $B(b \rightarrow s γ)$ and the other from the recent LEP data on $ε_b$. We have included one-loop vertex corrections to $Z \rightarrow b \overline b$ through $ε_b$ in the model. We find that the new $ε_b$ constraint excludes most of the less appealing window $\tanβ\lsim 1$ at $90\%$C.~L. for $m_t=150\GeV$. We also find that although $b \rightarrow s γ$ constraint is stronger for $\tanβ>1$, $ε_b$ constraint is stronger for $\tanβ\lsim 1$, and therefor…
We examine the possibilities of accommodating the muon $g-2$ anomaly reported by Fermilab in the 2HDM with a discrete $Z_4$ symmetry in which an inert Higgs doublet field ($H,~A,~H^\pm$) has the lepton flavor violation $μ$-$τ$ interactions. We study the case of light $H$ (5 GeV $<m_H<$ 115 GeV) and assume the Yukawa matrices to be real and symmetrical. Considering relevant theoretical and experimental constraints, especially for the multi-lepton searches at the LHC, we find the muon $g-2$ anomaly can be explained within $2σ$ range in the region of 5 GeV $<m_H<20$ GeV, 130 GeV $< m_A~(m_{H^\pm}…
We discuss the non-decoupling effects on the loop-induced $H^\pm W^\mp Z^0$ vertex in the general two Higgs-doublet model. The decay process $H^\pm \to W^\pm Z^0$ is analyzed at one-loop level and possible enhancement of the decay width is explored. We find that a novel enhancement can be realized by the Higgs non-decoupling effects with large mass difference between charged and CP-odd Higgs bosons. The branching ratio of the process can be a few % $\sim$ 10%. Therefore the decay mode may be detectable at LHC or future $e^+e^-$ linear colliders (LC's).
We find some constraints on the flavor changing vertices of the two Higgs doublet model, from the ΔM_{B_{d}} measurement. Although bounds from this observable have already been considered, this paper takes into account the role of a new operator not included previously, as well as the vertices ξ_{bb}, ξ_{tc} and ξ_{sb}. Using the Cheng-Sher parametrization, we found that for a relatively light charged Higgs boson (200-300 GeV), we get that λ_{tt}<1, while the parameter λ_{bb} could have values up to about 50. In addition, we use bounds for λ_{tt} and λ_{bb} obtained from B^{0}->X_{s}γat next t…
Concentrating on the impact of the very recent top quark discovery, we perform a combined analysis of two strongest constraints on the 2 Higgs doublet model, one coming from the recent measurement by CLEO on the inclusive branching ratio of b->s γdecay and the other from the recent LEP data on Z->b b-bar decay. We have included the model predictions for one-loop vertex corrections to Z->b b-bar through $ε_b$. We find that the $ε_b$ constraint excludes most of the less appealing window $\tanβ\lsim 1$ at 95% C.L. for the measured top mass from CDF, mt=176+/- 8+/-10 GeV. Moreover, it excludes $\t…
We consider the radiative decay $b\rightarrow s γ$, and the correction to the $Zb\overline{b}$ vertex in technicolor models with scalars. In these models, the scalar develops a vacuum expectation value when the technifermions condense, and the ordinary fermions develop masses via Yukawa couplings. Since the symmetry breaking sector involves both a fundamental scalar doublet and an isotriplet of composite scalars (the technipions), the phenomenology associated with the charged scalars is similar to that found in a type-I two-Higgs doublet model. We show that the correction to the $Zb\overline{b…
The $(g-2)_μ$ anomaly indicates that the second generation of leptons should have new interactions beyond the standard model. The high flux of $ν_μ$ and $\barν_μ$ at the forward experiments such as FASER$ν$ and SND@LHC makes them suitable setups to search for new interactions of the second generation leptons. In this paper, we build a model in which the second generation left-handed leptons couple to a new right-handed neutrino, $N$ and a new Higgs doublet which also couples to the quarks. The scattering of high energy $ν_μ$ off nuclei can produce $N$. We investigate how forward experiments ca…
We investigate the possibility of measuring the H^\pm W^\mp Z^0 vertex from the single $H^\pm$ production process via WZ fusion at the CERN Large Hadron Collider (LHC). This vertex strongly depends on the structure of the Higgs sector in various new physics scenarios, so that its measurement can be useful to distinguish the models. A signal and background simulation under the expected detector performance at the LHC is done for the processes of pp \to W^\pm Z^0 X \to H^\pm X \to tbX and pp \to W^\pm Z^0 X \to H^\pm X \to W^\pm Z^0 X, and the required magnitudes of the H^\pm W^\mp Z^0 vertex fo…
We compute the one loop right and left anomalous tensor couplings ($g_R$ and $g_L$, respectively) for the top quark, in the aligned two-Higgs-doublet model. They are the magnetic-like couplings in the most general parameterization of the $tbW$ vertex. We find that the aligned two-Higgs doublet model, that includes as particular cases some of the most studied extensions of the Higgs sector, introduces new electroweak contributions and provides theoretical predictions that are very sensitive to both new scalar masses and the neutral scalar mixing angle. For a large area in the parameters space w…
Extended scalar sectors with additional degrees of freedom appear in many scenarios beyond the Standard Model. Heavy scalar resonances that interact with the neutral current could be discovered via broad resonances in the tails of the four-lepton invariant mass spectrum, where the Standard Model background is small and well understood. In this article we consider a recent ATLAS measurement of four-lepton final states, where the data is in excess over the background for invariant masses above 500 GeV. We discuss the possibility that this excess could be interpreted as a "double peak" from the t…
The reactions e+e- -> t bar-c nu_e bar-nu_e, t bar-c e+ e- are very sensitive probes of the flavor-changing-scalar couplings which can occur in a model with one extra Higgs doublet. At the Next Linear Collider, with a center of mass energy of sqrt{s}=0.5--2 TeV, several hundreds and up to thousands of such events may be produced if the mass of the light neutral Higgs is a few hundred GeV. We also briefly comment on the decays t -> c W+ W-, t -> c Z Z. All of these reactions are severely suppressed in the Standard Model
We consider a framework where the Standard Model is augmented by a second SU(2) scalar doublet and by a real scalar singlet that, protected by a Z2 symmetry, provides a particle Dark Matter candidate. We show that this setup allows for doubly blind spots at both collider searches for anomalies in the Higgs invisible decay width, and at direct Dark Matter detection. The blind spots originate from cancellations between interfering diagrams featuring different neutral scalar exchanges, and from cancellations driven by the two-Higgs doublet structure in the vertex coupling the singlet state with t…
The inert 2-Higgs Doublet Model (i2HDM) is a well-motivated minimal consistent Dark Matter (DM) model, but it is rather challenging to test at the Large Hadron Collider (LHC) in the parameter space allowed by relic density and DM direct detection constraints. This is especially true when considering the latest XENON 1T data on direct DM searches which we use here to present the best current combined limit on the i2HDM parameter space. In this analysis, we present prospects to advance the exploitation of DM mono-jet signatures from the i2HDM at the LHC, by emphasising that a shape analysis of t…
There is a variety of new physics scenarios which deduce extended Higgs sectors in the low energy effective theory. The coupling of a singly-charged Higgs boson ($H^\pm$) with weak gauge bosons, $H^\pm W^\mp Z^0$, directly depends on the global symmetry structure of the model, so that its experimental determination can be useful to test each scenario. We discuss predictions on this coupling in several models, such as the model with additional real and complex triplets, the Littlest Higgs model, the two Higgs doublet model and the minimal supersymmetric standard model. In order to measure the $…
We study the constraints of the generic two-Higgs-doublet model (2HDM) type-III and the impacts of the new Yukawa couplings. For comparisons, we revisit the analysis in the 2HDM type-II. To understand the influence of all involving free parameters and to realize their correlations, we employ $χ$-square fitting approach by including theoretical and experimental constraints, such as S, T, and U oblique parameters, the production of standard model Higgs and its decay to $γγ$, $WW^*/ZZ^*$, $τ^+τ^-$, etc. The errors of analysis are taken at $68\%$, $95.5\%$, and $99.7\%$ confidence levels. Due to t…
The Two Higgs Doublet model and its phenomenological implications are discussed. A brief survey on the present status of this model is given. In particular, we concentrate on the Two Higgs Doublet Model with Flavor Changing Neutral Currents. First, we develop some new parametrizations of the 2HDM type III, in such a way that the relation of it with models type I and type II become apparent. Based on this parametrization we get some bounds on the mixing vertex involving the second and third lepton generations, and lower bounds on the mass of the pseudoscalar Higgs boson. Further, by using a par…
For the newly discovered $W$-boson mass anomaly, one of the simplest dark matter (DM) models that can account for the anomaly without violating other astrophysical/experimental constraints is the inert two Higgs doublet model, in which the DM mass ($m_{S}$) is found to be within $\sim 54-74$ GeV. In this model, the annihilation of DM via $SS\to b\bar{b}$ and $SS\to WW^{*}$ would produce antiprotons and gamma rays, and may account for the excesses identified previously in both particles. Motivated by this, we re-analyze the AMS-02 antiproton and Fermi-LAT Galactic center gamma-ray data. For the…
We explore the radiative corrections to the process $Z \to b \bar b$ in models with extended Higgs sectors. The observables $R_b = Γ(Z \to b \bar b)/Γ(Z \to \rm{hadrons})$ and the $Z b \bar b$ coupling asymmetry, $A_b = (g_L^2 - g_R^2)/(g_L^2 + g_R^2)$, are sensitive to these corrections. We present general formulae for the one-loop corrections to $R_b$ and $A_b$ in an arbitrary extended Higgs sector, and derive explicit results for a number of specific models. We find that in models containing only doublets, singlets, or larger multiplets constrained by a custodial $SU(2)_{c}$ symmetry so tha…
We study the contribution of charged Higgs boson to the rare decay of the top quark t->q+WZ (q=d,s,b) in models with Higgs sector that includes doublets and triplets. Higgs doublets are needed to couple charged Higgs with quarks, whereas the Higgs triplets are required to generate the non-standard vertex HWZ at tree-level. It is found that within a model that respect the custodial SU(2) symmetry and avoids flavour changing neutral currents by imposing discrete symmetries, the decay mode t->b+WZ, can reach a branching ratio of order 0.0178, whereas the decay modes t->(d,s)+WZ, can reach a simil…
The type-I two-Higgs-doublet model in the inverted Higgs scenario can retain the theoretical stability all the way up to the Planck scale. The Planck-cutoff scale, $Λ_{\rm cut}^{\rm Planck}$, directly impacts the mass spectra such that all the extra Higgs boson masses should be light below about 160 GeV. However, the observation of the light masses of new Higgs bosons does not indicate the high cutoff scale because a low cutoff scale can also accommodate the light masses. Over the viable parameter points that satisfy the theoretical requirements and the experimental constraints, we show that t…
We examine the leptophilic two Higgs doublet model with fermionic dark matter, considering the range of experimental constraints on the Higgs sector. The measurements of the 125 GeV Higgs from the LHC Run-I allow us to focus on those remaining processes that may play an important role at colliders. We find that the leptophilic model allows for a much lighter Higgs than in other two-Higgs models, although discovery at the LHC will be difficult. Adding a dark matter sector motivated by supersymmetric extensions of the leptophilic model, we find the existing parameter space can accommodate constr…
We explore the radiative corrections to the process Z --> b b-bar in models with extended Higgs sectors. The observables R_b (the Z hadronic branching fraction to b b-bar) and the b-quark asymmetry A_b = (g_L^2 - g_R^2)/(g_L^2 + g_R^2) are sensitive to these corrections. We find that in models containing only Higgs doublets, singlets, or larger multiplets constrained by a custodial SU(2) symmetry, the radiative corrections to R_b involving charged Higgs bosons always worsen the Standard Model fit to electroweak data. Thus, the present R_b data can be used to set lower bounds on the charged Hig…
The Supersymmetric SO(10) GUT based on the ${\bf{210\oplus 10\oplus 120\oplus 126\oplus {\bar{126}}}}$ Higgs system has 40 real superpotential parameters of which 2 can be fixed by the Light Higgs doublet fine tuning and one by the determination of the unification scale by the RG flow. It provides a minimal framework for the emergence of R-parity exact Supersymmetric Standard Model at low energies and viable supersymmetric seesaw explanation for the observed neutrino masses and mixing angles. We present complete formulae for MSSM decomposition of the superpotential invariants, explicit GUT sca…
A fermion dark matter candidate with a relic abundance set by annihilation through a pseudoscalar can evade constraints from direct detection experiments. We present simplified models that realize this fact by coupling a fermion dark sector to a two-Higgs doublet model. These models are generalizations of mixed bino-Higgsino dark matter in the MSSM, with more freedom in the couplings and scalar spectra. Annihilation near a pseudoscalar resonance allows a significant amount of parameter space for thermal relic dark matter compared to singlet-doublet dark matter, in which the fermions couple onl…
We study masses and decay widths of positive and negative parity nucleons using a three-flavor parity doublet model, in which we introduce three representations, $\left[({\bf 3} , \bar{\bf 3})\oplus (\bar{\bf 3} , {\bf 3})\right]$, $\left[({\bf 3} , {\bf 6}) \oplus ({\bf 6}, {\bf 3})\right]$, and $\left[({\bf 8} , {\bf 1}) \oplus ({\bf 1} , {\bf 8})\right]$ of the chiral U$(3)_{\rm L}\times$U$(3)_{\rm R}$ symmetry. We find an extended version of the Goldberger-Treiman relation among the mass differences and the coupling constants for pionic transitions. This relation leads to an upper bound fo…
We present a fit to the 2012 LHC Higgs data in different supersymmetric frameworks using naturalness as a guiding principle. We consider the MSSM and its D-term and F-term extensions that can raise the tree-level Higgs mass. When adding an extra chiral superfield to the MSSM, three parameters are needed determine the tree-level couplings of the lightest Higgs. Two more parameters cover the most relevant loop corrections, that affect the hγγand hgg vertexes. Motivated by this consideration, we present the results of a five parameters fit encompassing a vast class of complete supersymmetric theo…
The LHC searches for the CP-odd Higgs boson is studied (with masses from 300 GeV to 1 TeV) in the context of the general two-Higgs-doublet model. With the discovery of the 125 GeV Higgs boson at the LHC, we highlight one promising discovery channel of the hZ. This channel can become significant after the global signal fitting to the 125 GeV Higgs boson in the general two-Higgs-doublet model. It is particularly important in the scenario where two CP-even Higgs bosons in the two-Higgs-doublet model have the common mass of 125 GeV. Since the final states involve a Standard-Model-like Higgs boson,…
The vertex H^+_αW^-h^0_β, involving the gauge boson W^+- and the charged (H^+-_α) and neutral Higgs bosons (h^0_β), arises within the context of many extensions of the SM, and it can be used to probe the quantum numbers of the Higgs multiplet. After presenting a general discusion for the expected form of this vertex with arbitrary Higgs representations, we discuss its strength for several specific models, which include: i) the Two-Higgs Doublet Model (THDM), both the generic and the SUSY case, and ii) models with additional Higgs triplets, including both SUSY and non-SUSY cases. We find that i…
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 (BSM). We illustrate this by focusing on the Type-II two Higgs doublet model. A multi-variable global fitting is performed with full one loop contributions to relevant couplings. The Higgs signal strength measurements at proposed Higgs factories can provide strong constraints on new physics and are found to be complementary to the Z-pole measurements.
We propose a two Higgs doublet Type III seesaw model with $μ$-$τ$ flavor symmetry. We add an additional SU(2) Higgs doublet and three SU(2) fermion triplets in our model. The presence of two Higgs doublets allows for natural explanation of small neutrino masses with triplet fermions in the 100 GeV mass range, without fine tuning of the Yukawa couplings to extremely small values. The triplet fermions couple to the gauge bosons and can be thus produced at the LHC. We study in detail the effective cross-sections for the production and subsequent decays of these heavy exotic fermions. We show for …
