The Supersymmetric Custodial Triplet Model (SCTM) adds to the particle content of the MSSM three $SU(2)_L$ triplet chiral superfields with hypercharge $Y=(0,\pm1)$. At the superpotential level the model respects a global $SU(2)_L \otimes SU(2)_R$ symmetry only broken by the Yukawa interactions. The pattern of vacuum expectation values of the neutral doublet and triplet scalar fields depends on the symmetry pattern of the Higgs soft breaking masses. We study the cases where this symmetry is maintained in the Higgs sector, and when it is broken only by the two doublets attaining different vacuum expectation values. In the former case, the symmetry is spontaneously broken down to the vectorial subgroup $SU(2)_V$ and the $ρ$ parameter is protected by the custodial symmetry. However in both situations the $ρ$ parameter is protected at tree level, allowing for light triplet scalars with large vacuum expectation values. We find that over a large range of parameter space, a light neutralino can supply the correct relic abundance of dark matter either through resonant s-channel triplet scalar funnels or well tempering of the Bino with the triplet fermions. Direct detection experiments have trouble probing these model points because the custodial symmetry suppresses the coupling of the neutralino and the $Z$ and a small Higgsino component of the neutralino suppresses the coupling with the Higgs. Likewise the annihilation cross sections for indirect detection lie below the Fermi-LAT upper bounds for the different channels.
We analyze the extension of the Minimal Supersymmetric Standard Model which includes extra Y=(0,\pm 1) supersymmetric triplets with a global SU(2)_L \otimes SU(2)_R symmetry spontaneousy broken to the custodial SU(2)_V by the vacuum expectation value of the neutral scalar components of doublets and triplets. The model is the supersymmetrization of the non-supersymmetric model introduced long ago by Georgi and Machacek where the ρ-parameter is kept to unity at the tree-level by the custodial symmetry. Accordingly the scalar sector is classified into degenerate SU(2)_V multiplets: singlets, trip…
The Supersymmetric Custodial Triplet Model, a supersymmetric generalization of the Georgi-Machacek model, has proven to be an interesting modification of the MSSM. It extends the MSSM Higgs sector by three extra SU(2)L triplets in such a way that approximate custodial invariance is preserved and rho-parameter deviations are kept under control. By means of a sizeable triplet contribution to electroweak breaking the model is able to generate a barrier at tree level between the false vacuum and the electroweak one. This will result in a strong first order phase transition for an important region …
We study bounds on Higgs boson masses from perturbative unitarity in the Georgi-Machacek model, whose Higgs sector is composed of a scalar isospin doublet, a real and a complex isospin triplet fields. This model can be compatible with the electroweak precision data without fine tuning because of the imposed global SU(2)_R symmetry in the Higgs potential, by which the electroweak rho parameter is unity at the tree level. All possible two-body elastic-scattering channels are taken into account to evaluate the S-wave amplitude matrix, and then the condition of perturbative unitarity is imposed on…
Higgs triplet models are known to have difficulties obtaining agreement with electroweak precision data and in particular constraints on the $ρ$ parameter. Either a global $SU(2)_L \otimes SU(2)_R$ symmetry has to be imposed on the scalar potential at the electroweak scale, as done in the well-known Georgi-Machacek (GM) model, or the triplet vacuum expectation values must be very small. We construct a supersymmetric model that can satisfy constraints on the $ρ$ parameter, even if these two conditions are not fulfilled. We supersymmetrize the GM model by imposing the $SU(2)_L \otimes SU(2)_R$ s…
Original Georgi-Machacek model can preserve the custodial symmetry at tree level after the electroweak symmetry breaking. Unless additional $SU(2)_c$ custodial symmetry breaking effects are significant, the new physics contributions to $Δm_W$ are always very small. Our numerical results show that ordinary GM model can contribute to $Δm_W$ a maximal amount $0.0012$ GeV, which can not explain the new CDF-II anomaly on W boson mass. We propose firstly to introduce small misalignment among the triplet VEVs to increase $Δm_W$, which can give large new physics contributions to $Δm_W$. Such slightly …
The Georgi-Machacek model, introducing a complex and a real scalar triplet as additional components of the electroweak symmetry breaking sector, enables substantial triplet contributions to the weak gauge boson masses, subject to the equality of the complex and the real triplet vacuum expectation values (vev) via a custodial SU(2) symmetry. We present an updated set of constraints on this scenario, from collider data (including those from 137/139~fb$^{-1}$ of luminosity at the Large Hadron Collider), available data on the 125-GeV scalar, indirect limits and also theoretical restrictions from v…
The breakdown of E_6 within the supersymmetric (SUSY) Grand Unified Theories (GUTs) can result in SUSY extensions of the standard model (SM) based on the SM gauge group together with extra U(1) gauge symmetry under which right-handed neutrinos have zero charge. In these U(1)_N extensions of the minimal supersymmetric standard model (MSSM) a single discrete \tilde{Z}^H_2 symmetry may be used to suppress the most dangerous operators, that give rise to proton decay as well as non-diagonal flavour transitions at low energies. The SUSY models under consideration involves Z' and extra exotic matter …
The observation of diphoton excess around the mass of 750 GeV in LHC Run-II motivates us to consider whether the singlet Higgs boson in the custodial Higgs triplet model can serve as a good candidate because an earlier study of comprehensive parameter scan shows that it can have the right mass in the viable mass spectra. By assuming the singlet Higgs mass at 750 GeV, its total width less than 50 GeV and imposing constraints from the LHC 8-TeV data, we identify an approximately linear region on the $(v_Δ, α)$ plane along which the exotic Higgs boson masses satisfy a specific hierarchy and have …
Composite Higgs models based on SU(5)/SO(5) are characterised by the presence of custodial triplets, like the Georgi-Machacek model. We classify all the operators giving rise to the top mass and Higgs potential in presence of fermion partial compositeness, with top partners in two-index representations of SU(5). A detailed study of each operator allows us to find correlations in the couplings of Higgs and non-Higgs pseudo-Nambu-Goldstone bosons, which depend only on one, two or three independent parameters. We also analyse the Higgs potential, finding that a misalignment along the custodial in…
In an SU(2) gauge theory, if the gauge bosons turn out to be degenerate after spontaneous symmetry breaking, obviously these mass terms are invariant under a global SU(2) symmetry that is unbroken. The pure gauge terms are also invariant under this symmetry. This symmetry is called the {\em custodial symmetry} (CS). In $\rm SU(2)\times U(1)$ gauge theories, CS implies a mass relation between the $W$ and the $Z$ bosons. The Standard Model (SM), as well as various extensions of it in the scalar sector, possess such a symmetry. In this paper, we critically examine the notion of CS and show that t…
We study the effects of custodial symmetry violation in the Georgi-Machacek (GM) model. The GM model adds isospin-triplet scalars to the Standard Model in a way that preserves custodial symmetry at tree level; however, this custodial symmetry has long been known to be violated at the one-loop level by hypercharge interactions. We consider the custodial-symmetric GM model to arise at some high scale as a result of an unspecified ultraviolet completion, and quantify the custodial symmetry violation induced as the model is run down to the weak scale. The measured value of the eletroweak rho param…
The model proposed by Georgi and Machacek enables the Higgs sector to involve isospin triplet scalar fields while retaining a custodial $SU(2)_V$ symmetry in the potential and thus ensuring the electroweak $ρ$ parameter to be one at tree level. This custodial symmetry, however, is explicitly broken by loop effects of the $U(1)_Y$ hypercharge gauge interaction. In order to make the model consistent at high energies, we construct the most general form of the Higgs potential without the custodial symmetry, and then we derive the one-loop $β$-functions for all the model parameters. Assuming the $δ…
The generalization of the "custodial symmetry" mechanism which leads to the natural (without fine tuning) explanation of the doublet-triplet hierarchy is suggested in the frames of extended $SU(N\geq 8)$ SUSY GUTs. It is shown also that such type of SUSY GUT can predict the value of strong gauge coupling constant $α_S(M_Z)$ consistent with present experimental data.
The Georgi-Machacek model adds two SU(2)_L-triplet scalars to the Standard Model in such a way as to preserve custodial SU(2) symmetry. We study the generalizations of the Georgi-Machacek model to SU(2)_L representations larger than triplets. Perturbative unitarity considerations limit the possibilities to models containing only SU(2)_L quartets, quintets, or sextets. These models are phenomenologically interesting because they allow the couplings of the 125 GeV Higgs boson to WW and ZZ to be larger than their values in the Standard Model. We write down the most general custodial SU(2)-preserv…
The Georgi-Machacek (GM) model is one of many Beyond Standard Model scenarios with an extended scalar sector which can group under the custodial $\rm SU(2)_C$ symmetry into a fiveplet, a triplet, and two singlets. The heavy charged custodial fiveplet Higgs $\rm H_5^{\pm}$ are typical particles in GM model which couple to the electroweak gauge bosons, therefore provide a good testing ground for the detection of the $\rm H^\pm W^\mp Z$ vertex. The neutral custodial fiveplet Higgs $\rm H_5^{0}$ in the GM model has the same mass with $\rm H_5^{\pm}$ and couples to the electroweak gauge bosons $\rm…
Gauge mediated supersymmetry breaking (GMSB) is an elegant mechanism to transmit supersymmetry breaking from the hidden to the MSSM observable sector, which solves the supersymmetric flavor problem. However the smallness of the generated stop mixing requires superheavy stops to reproduce the experimental value of the Higgs mass. Two possible ways out are: i) To extend GMSB by direct superpotential messenger-MSSM Yukawa couplings to generate sizeable mixing, thus reintroducing the flavor problem; ii) To extend the MSSM Higgs sector with singlets and/or triplets providing extra tree-level correc…
In this note, a ``littlest higgs'' model is presented which has an approximate custodial SU(2) symmetry. The model is based on the coset space $SO(9)/(SO(5)\times SO(4))$. The light pseudo-goldstone bosons of the theory include a {\it single} higgs doublet below a TeV and a set of three $SU(2)_W$ triplets and an electroweak singlet in the TeV range. All of these scalars obtain approximately custodial SU(2) preserving vacuum expectation values. This model addresses a defect in the earlier $SO(5)\times SU(2)\times U(1)$ moose model, with the only extra complication being an extended top sector. …
A solution of the doublet-triplet splitting problem in the supersymmetric $SU(6)$ gauge theory is suggested. The `missing doublet' multiplet -- 175-plet of the $SU(6)$ group as well as the custodial $SU(2)_{cus}$ global symmetry play crucial role for achieving the doublet-triplet hierarchy. Two examples in which the doublet-triplet splitting occurs naturally are presented.
We study how the custodial symmetry in the Higgs sector of the Georgi-Machacek (GM) model can be tested at the LHC. As the minimal extension of the Higgs triplet model, in which tiny neutrino masses are generated via the Type-II Seesaw Mechanism, the GM model keeps the electroweak $ρ$ parameter at unity at tree level. In the GM model, there are 5-plet ($H_5$), 3-plet ($H_3$) and singlet ($H_1$) Higgs bosons under the classification of the custodial $SU(2)_V$ symmetry, in addition to the standard model-like Higgs boson ($h$). These new Higgs bosons have the following characteristic features at …
The mechanism of gauge mediated supersymmetry breaking (GMSB) solves the supersymmetric flavor problem although it requires superheavy stops to reproduce the experimental value (125 GeV) of the Higgs mass. A possible way out is to extend the MSSM Higgs sector with triplets which provide extra tree-level corrections to the Higgs mass. Triplets with neutral components getting vacuum expectation values (VEV) have the problem of generating a tree-level correction to the ρparameter. We introduce supersymmetric triplets with hypercharges Y=(0,\pm 1), with a tree-level custodial SU(2)_L\otimes SU(2)_…
We discuss the vacuum structure of a version of the Georgi-Machecek model with an exact $\mathbb{Z}_2$ symmetry acting on the triplet fields. Besides the usual custodial-symmetric model, with $ρ=1$ at tree-level, a model with a dark matter candidate is also viable. The other phases of the model lead to electric charge breaking, a wrong pattern of electroweak symmetry breaking or to $ρ\neq 1$ at tree-level. We derive conditions to have an absolute minimum in each of the two viable phases, the custodial and the dark matter phases.
We construct a supersymmetric version of the triplet Higgs model for neutrino masses, which can generate a baryon asymmetry of the Universe through lepton-number violation and is consistent with the gravitino constraints.
The supersymmetric standard model of particle interactions is extended to include two Higgs triplet superfields at the TeV scale, carrying two units of lepton number. Realistic tree-level Majorana neutrino masses are obtained in the presence of soft, i.e. bilinear, R-parity nonconservation.
In the supersymmetric triplet (type-II) seesaw model, in which a single SU(2)_L-triplet couples to leptons, the high-energy neutrino flavour structure can be directly determined from the low-energy neutrino data. We show that even with such a minimal triplet content, leptogenesis can be naturally accommodated thanks to the resonant interference between superpotential and soft supersymmetry breaking terms.
We propose a renormalizable supersymmetric SO(10) model where the doublet-triplet splitting problem is solved using the Dimopoulos-Wilczek mechanism. An unwanted coupling is forbidden through a filter sector. To suppress proton decay without spoiling gauge coupling unification, there is a problem in the weak doublets which requires further improvements.
The supersymmetric type II seesaw may leave a limit where a triplet boson along with the standard Higgs boson remains light. Working in this limit with small triplet vacuum expectation vlaues, we explore how much such a light triplet boson can contribute to the Higgs boson decay to diphoton, and analyze the feasibility to observe it through same-sign di-lepton and tetra-lepton signals in the forthcoming LHC run after setting a LHC7 limit in a simplified parameter space of the triplet vaccum expectation value and the doubly charged boson mass.
We construct a supersymmetric SO(10) model, where natural doublet-triplet splitting implemented via the Dimopoulos-Wilczek mechanism is stable under the addition of 126+\bar{126} Higgs superfields needed to generate the small neutrino masses via the see-saw mechanism and where both the charged fermion and neutrino masses arise from just one set of 10 and \bar{126} multiplets.
We study an extension of the minimal supersymmetric standard model with a zero hypercharge triplet, and the effect that such a particle has on stop decays. This model has the capability of predicting a 125.5 GeV Higgs even in the presence of light stops and it can modify the diphoton rate by means of the extra charged fermion triplet coupled to the Higgs. Working in the limit where the scalar triplet decouples, and with small values of mA, we find that the fermion triplet can greatly affect the branching ratios of the stops, even in the absence of a direct stop-triplet coupling. We compare the…
We argue that the consistent implementation of the multiple point principle (MPP) in the general non-supersymmetric two Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in the Higgs sector and the absence of flavour changing neutral currents (FCNC) in the considered model. In particular the existence of a large set of degenerate vacua at some high energy scale $Λ$ caused by the MPP can result in approximate U(1) and Z(2) symmetries that suppress FCNC and CP--violating interactions in the 2HDM. We explore the renormalisation gro…
We present a realistic supersymmetric SU(6) model which implements doublet-triplet splitting by the missing vev mechanism. The model makes use of only the simplest representations, requires no fine tuning of parameters and maintains coupling constant unification as a prediction. Fermion masses also emerge in a very straightforward manner. This is the first time that the missing vev mechanism has been realized in the context of SU(6).
In supersymmetric models the presence of Higgs triplets introduce new quartic interactions for the doublets that may raise the mass of the lightest CP-even field up to 205 GeV. We show that the complete effect of the triplets can be understood by decoupling them from the minimal sector and then analyzing the vacuum and the spectrum of the two-Higgs doublet model that results. We find that the maximum value of m_h is only achieved in a very definite region of the parameter space. In this region, however, radiative corrections decrease the bound to 190 GeV.
We summarize the results on patterns of flavour violation in a Randall-Sundrum model with custodial protection (RSc) and compare them with those identified in the Littlest Higgs Model with T--parity (LHT) and in a number of SUSY Flavour Models. While K decays play in this presentation a prominent role, the inclusion of B physics and lepton flavour violation is crucial in the distinction between these three popular extensions of the Standard Model (SM) by means of flavour physics.
In the minimum supersymmetric SU(5) GUT, we derive the upper limit on the mass of the color-triplet Higgs multiplets as $\mhc\leq 2.4\times 10^{16}~\GEV$ (90 \% C.L.) taking all possible corrections into account in a renormalization group analysis. If the above upper limit is compared with a limit on $\mhc$ from the negative search for the proton decay; $\mhc \geq 2.0\times 10^{16}~\GEV$ (in which effects of the larger top-quark mass are included), the minimum supersymmetric SU(5) GUT is severely constrained.
We find that, at the one-loop level, the spontaneous CP violation is possible in a supersymmetric standard model that has an extra chiral Higgs triplet with hypercharge Y=0. At the tree level, this triplet-extended supersymmetric standard model (TESSM) cannot have any reasonable parameter spaces for the spontaneous CP violation, because the experimental constraints on the coupling coefficient of the neutral Higgs boson to a pair of $Z$ bosons exclude them. By contrast, at the one-loop level, we find that there are experimentally allowed parameter regions, where the spontaneous CP violation may…
Lepton flavor violating processes such as μ\to 3e and μ\to e γare investigated with supersymmetric Higgs triplet pair Δand \bar Δin the light of neutrino masses and experimentally verifiable leptogenesis. The Higgs triplet mass M_Δis expected to be in the range of 1 - 100 TeV. The branching ratios of these charged lepton decays are evaluated in terms of M_Δand the coupling f L ΔL of Higgs triplet Δwith lepton doublet pairs L L, which is proportional to the neutrino mass matrix. They may be reached in the future collider experiments. In particular, the μ\to 3e decay would be observed indicating…
The leptogenesis with supersymmetric Higgs triplets is studied in the light of experimental verification in the TeV region. The lepton number asymmetry appears just after the inflation via multiscalar coherent evolution of Higgs triplets and antislepton on a flat manifold. If the Higgs triplet mass terms dominate over the negative thermal-log term for the Hubble parameter H comparable to the Higgs triplet mass M_Δ, the asymmetry is fixed readily to some significant value by the redshift and rotation of these scalar fields, providing the sufficient lepton-to-entropy ratio n_L / s \sim 10^-10. T…
The discovery of a standard model (SM)-like Higgs boson with a relatively heavy mass $m_h$ and hints of di-photon excess has deep implication to supersymmetric standard models (SSMs). We consider the SSM extended with hypercharge $\pm1$ triplets, and investigate two scenarios of it: (A) Triplets significantly couple to the Higgs doublets, which can substantially raise $m_h$ and simultaneously enhance the Higgs to di-photon rate via light chargino loops; (B) Oppositely, these couplings are quite weak and thus $m_h$ can not be raised. But the doubly-charged Higgs bosons, owing to the gauge group…
The breakdown of E_6 gauge symmetry at high energies may lead to supersymmetric (SUSY) models based on the Standard Model (SM) gauge group together with extra U(1)_ψ and U(1)_χ gauge symmetries. To ensure anomaly cancellation the particle content of these E_6 inspired models involves extra exotic states that generically give rise to non-diagonal flavour transitions and rapid proton decay. We argue that a single discrete \tilde{Z}^{H}_2 symmetry can be used to forbid tree-level flavor-changing transitions, as well as the most dangerous baryon and lepton number violating operators. We present 5D…
The recent discovery of the $\sim 125$ GeV Higgs boson by Atlas and CMS experiments has set strong constraints on parameter space of the minimal supersymmetric model (MSSM). However these constraints can be weakened by enlarging the Higgs sector by adding a triplet chiral superfield. In particular, we focus on the $Y=0$ triplet extension of MSSM, known as TESSM, where the electroweak contributions to the lightest Higgs mass are also important and comparable with the strong contributions. We discuss this in the context of the observed Higgs like particle around 125 GeV and also look into the st…
We construct a natural model of the supersymmetric SU(6) unification, in which the symmetry breaking, down to the standard model gauge group, results in the number of pseudo-Nambu-Goldstone superfields with interesting properties. Namely, besides the Higgs doublet-antidoublet pair which is responsible for the electroweak phase transition, the Nambu-Goldstone sector consists of multiplets in the anti- and fundamental representations of SU(5). While being strictly massless in the supersymmetric limit, they acquire the weak scale masses as a result of its breaking. The color-triplet components of…
We point out that in non supersymmetric GUTs, in which the SU(5) gauge symmetry is broken down to the Standard Model gauge group by a $\mathbf{24}$ Higgs multiplet the Appelquist-Carazzone decoupling is violated. This is because the $SU(2)_L$ Higgs triplet contained in the $\mathbf{24}$ acquires a dimensionfull coupling to the $SU(2)_L$ Higgs doublets which is proportional to the GUT breaking vacuum expectation value (VEV) $V$. As a result, at one loop heavy gauge and Higgs fields contribution to tadpoles generate a VEV of the triplet which is not suppressed for $V\to\infty$ and violates the c…
We consider the doublet-triplet fermionic model in the scheme of the custodial limit when the dark matter (DM) candidate is pure doublet and lies at the electroweak scale. This scheme, despite being an appealing and promising DM model, is severely constrained by the interplay between the DM relic density constraint and the LHC measurement of the Higgs diphoton decay rate. In this work, the DM relic density is considered to arise from either a nonstandard cosmology scenario or as a part of a larger sector encompassing other DM particles, this in order to saturate the observed relic abundance. F…
We propose a new possibility to reconcile the coupling unification scenario with the triplet-doublet mass splitting based on a 5-dimensional supersymmetric model with SU(5) gauge symmetry. It is shown that the minimal supersymmetric standard model is derived on a 4-dimensional wall through compactification on $S^1/(Z_2 \times Z_2')$.
We investigate a supersymmetric extension of the Minimal Supersymmetric Standard Model (MSSM), called the TNMSSM, containing a $SU(2)$ Higgs triplet $(\hat{T})$ of $Y=0$ hypercharge and a singlet superfields $(\hat{S})$ in the corresponding superpotential. The model can be viewed, equivalently, as an extension of the NMSSM with the addition of a $\hat{T}-\hat{S}$ interaction and of an extra coupling of the triplet to the two Higgs doublets of the NMSSM. In this scenario the Higgs particle spectrum at tree-level gets additional mass contributions from the triplet and singlet scalar components r…
We have conceived a supersymmetric Type II seesaw model at TeV scale, which has some additional particles consisting of scalar and fermionic triplet Higgs states, whose masses being around few hundred GeV. In this particular model, we have studied constraints on the masses of triplet states arising from the lepton flavor violating (LFV) processes, such as $μ\to 3e$ and $μ\to eγ$. We have analyzed the implications of these constraints on other observable quantities such as the muon anomalous magnetic moment and the decay patterns of scalar triplet Higgses. Scalar triplet Higgs states can decay …
Recent results on Higgs searches at the LHC point towards the existence of a Higgs boson with mass of about 126 GeV whose diphoton decay rate tends to be larger than in the Standard Model. These results are in tension with natural MSSM scenarios: such a Higgs mass requires heavy (third-generation) squarks which reintroduce some amount of fine-tuning and in general the Higgs diphoton decay rate tends to follow the Standard Model result. In this paper we prove that these problems can be alleviated by introducing an extra supersymmetric triplet coupled to the Higgs in the superpotential. This sup…
The CDF collaboration has recently published a precision measurement of the W-boson mass that differs from the Standard Model prediction by seven standard deviations. This result can be explained with additional electroweak multiplets that either break the custodial symmetry or contribute to oblique parameters at loop level. Here, we study one of the best-motivated scenarios involving new multiplets: the type-II seesaw model, which involves a scalar triplet that generates Majorana neutrino masses and can furthermore resolve the W-boson mass discrepancy. This favors a doubly-charged scalar with…
We present a new mechanism for doublet-triplet splitting in supersymmetric SO(10) models using a missing vev pattern which is different from the one used in the currently popular Dimopoulos-Wilczek method. In our method, the doublets in a {$\bf 16,\bar{16}$} pair are the ones split from the rest of the multiplet and are then mixed with the doublets from one or two {\bf 10}'s giving rise to the doublets {$\bf H_u$} and {$\bf H_d$} of the standard model. This approach provides a natural way to understand why top quark is so much heavier than the bottom quark. It also enables us to generate both …
We revisit an extension of the MSSM by adding a hypercharge-neutral, SU(2)-triplet chiral superfield. Similar to the NMSSM, the triplet gives an additional contribution to the quartic coupling in the Higgs potential, and the mass of the lightest CP-even Higgs boson can be greater than tne mass of the Z-bosn at tree-level. In addition to discussing the perturbativity, fine-tuning, and decoupling issues of this model, we compute the dominant 1-loop corrections to the mass of the lightest CP-even Higgs boson from the triplet sector. When the Higgs-Higgs-Triplet coupling in the superpotential is c…
We investigate an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet. We focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV in the spectrum, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. The triplet extension gives rise to two additional charged Higgs bosons which do not couple to fermions but can decay into $Z W^\pm$. The presence of a very light pseudoscalar opens $a_1 W^\pm$ decay mode for the light charged …
We propose a new mechanism towards the solution to the doublet-triplet Higgs mass splitting problem in the supersymmetric grand unified theory. Our model is based on the gauge group $SU(5)_H \times SU(5)_{GUT}$, where $SU(5)_H$ and $SU(5)_{GUT}$ are a new strong gauge interaction and the ordinary grand unified gauge group, respectively. The doublet-triplet Higgs mass splitting is realized through the quantum deformation of moduli space caused by the strong $SU(5)_H$ gauge dynamics. The low energy description of our model is given by the minimal supersymmetric standard model.
There is a good reason why the standard electroweak SU(2) X U(1) gauge model may be supplemented by two Higgs scalar doublets. They may be remnants of the spontaneous breaking of an SU(2) X SU(2) X U(1) gauge symmetry at a much higher energy scale. In one case, the two-doublet Higgs potential has a custodial SU(2) symmetry and implies an observable scalar triplet. In another, a light neutral scalar becomes possible.
We present a detailed study of the Higgs sector within an extension of the Minimal Supersymmetric Standard Model that includes one Complex Higgs Triplet (MSSM+1CHT). The model spectrum includes three singly charged Higgs bosons as well as three CP-even (or scalar) and two CP-odd (or pseudoscalar) neutral Higgs bosons. We present an approximated calculation of the one-loop radiative corrections to the neutral CP-even Higgs masses ($m_{H_i^0}$) and the couplings $H_i^0 Z^0 Z^0$ ($i=1$, 2, 3), which determine the magnitude of the Higgs-strahlung processes $e^+ e^-\to Z^0 H^0_i$. Limits from LEP2 …
