Triplet Higgs Fields Research Articles

CP violation in a model with Higgs triplets

We discuss CP-violation in a model with a real and a complex isospin triplet Higgs fields without introducing any symmetries except for the electroweak gauge symmetry. This corresponds to the minimal extension of the Higgs sector with the following properties: (i) providing new source of CP violation, (ii) absence of quark flavor changing neutral currents at tree level, and (iii) enabling the electroweak rho parameter to be unity at tree level in the scenario without imposing any new symmetries. Our model can be regarded as the generalized version of the Georgi-Machacek model, in which the global SU(2)L × SU(2)R symmetry is explicitly broken due to CP-violating terms in the potential. We present analytic formulas for theoretical constraints from perturbative unitarity and vacuum stability as well as contributions to the electron electric dipole moment (EDM) and the neutron EDM from all the Barr-Zee type diagrams. We then examine the parameter space allowed by the constraints mentioned above and also those from the uniqueness of the vacuum, measurements at Tevatron and LHC by using HEPfit to perform a global parameter fit. We find that the decays of the two lightest extra neutral (singly-charged) scalars, H1 and {H}_2left({H}_1^{pm}right) , into hZ (WZ) can be significant at the same time under the constraints, which can serve as direct evidence of CP violation in our model, but not from models with multi-doublet extensions.

Dirac dark matter, dark radiation, and the type-II seesaw mechanism in alternative U(1)X standard model

We propose an extra $U(1{)}_{X}$ model with an alternative charge assignment for right-handed neutrinos. The type-II seesaw mechanism by a triplet Higgs field is promising for neutrino mass generation because of the alternative charge assignment. The small vacuum expectation value (VEV) of an additional Higgs doublet naturally leads to a very small VEV of the triplet Higgs field, and as a result, the smallness of neutrino mass can be understood. With the minimal Higgs field for $U(1{)}_{X}$ with the charge 1, right-handed neutrinos are candidates for Dirac dark matter (DM) and dark radiation (DR). We have derived and imposed the LHC bound, the DR constraint, and the bound from DM direct searches in the wide range of parameter space. Among various $U(1{)}_{X}$ choices, the DM direct search bound is found to be weakest for $U(1{)}_{R}$ where the constraints from thermal DM and non-negligible DR can be compatible. Such a number of the effective neutrino species would be interesting from the viewpoint of the so-called Hubble tension.

Implication of the W boson mass anomaly at CDF II in the Higgs triplet model with a mass difference

A new report for the measurement of the W boson mass has been provided by the CDF II experiment. The measured value of the W boson mass is given to be mWCDF II=80.4335±0.0094 GeV which shows 7σ deviation from the standard model prediction, while the other groups of high energy experiments, e.g., ATLAS and D0 II, show consistent results with the latter. Assuming that the measurement at CDF II is correct, we discuss the possibility to explain the anomaly in the Higgs triplet model. We find that the anomaly can be explained under the constraints from the electroweak rho parameter, the effective weak mixing angle, the partial width of the leptonic Z decay and current direct searches at LHC when non-zero mass differences among the triplet-like Higgs bosons and the vacuum expectation value of the triplet Higgs field are taken to be O(100) GeV and O(1) GeV, respectively.

Topologically stable, finite-energy electroweak-scale monopoles

The existence of a magnetic monopole, if it exists, remains elusive. Experimental searches have been carried out and are continuing in this quest. Of great uncertainty is the mass of the monopole which is model-dependent and ranging from some Grand Unified scale to the electroweak scale. In this paper, we propose a model where topologically stable, finite-energy monopoles à la 't Hooft-Polyakov could exist with a mass proportional to the electroweak scale. This comes about in a model of neutrino masses where right-handed neutrinos are non-sterile whose electroweak-scale Majorana masses are obtained by the coupling to a complex triplet Higgs field. Custodial symmetry which insures MW=MZcos⁡θW requires the introduction of another triplet Higgs field but real this time. It is this real Higgs triplet that is at the core of our proposal.

Type II seesaw models with modular A4 symmetry

We discuss type-II seesaw models adopting modular $A_4$ symmetry in supersymmetric framework. In our approach, the models are classified by the assignment of $A_4$ representations and modular weights for leptons and triplet Higgs fields. Then neutrino mass matrix is characterized by modulus $\tau$ and two free parameters. Carrying out numerical analysis, we find allowed parameter sets which can fit the neutrino oscillation data. For the allowed parameter sets, we obtain the predictions in neutrino sector such as CP violating phases and the lightest neutrino mass. Finally we also show the predictions for the branching ratios of doubly charged scalar boson focusing on the case where the doubly charged scalar boson dominantly decays into charged leptons.

SU(3)C×SU(3)L×U(1)X model from SU(6)

We propose the $SU(3)_C\times SU(3)_L\times U(1)_X$ model arising from $SU(6)$ breaking. One family of the Standard Model (SM) fermions arises from two $\bar{6}$ representations and one $15$ representation of $SU(6)$ gauge symmetry. To break the $SU(3)_C\times SU(3)_L\times U(1)_X$ gauge symmetry down to the SM, we introduce three $SU(3)_L$ triplet Higgs fields, where two of them come from the $\bar{6}$ representation while the other one from the $15$ representation. We study the gauge boson masses and Higgs boson mass in detail, and find that the vacuum expectation value (VEV) of the Higgs field for $SU(3)_L\times U(1)_X$ gauge symmetry breaking is around 10 TeV. The neutrino masses and mixing can be generated via the littlest inverse seesaw mechanism. In particular, we have normal hierarchy for neutrino masses and the lightest active neutrino is massless. Also, we consider constraints from the charged lepton flavor changing decays as well. Furthermore, introducing two $SU(3)_L$ adjoint fermions, one $SU(3)_C$ adjoint scalar, and one $SU(3)_L$ triplet scalar, we can achieve gauge coupling unification within 1\%. These extra particles can provide a dark matter candidate as well.

Magnetic Monopoles in Multivector Boson Theories

A classical solution for a magnetic monopole is found in a specific multivector boson theory. We consider the model whose [SU(2)]N+1 gauge group is broken by sigma model fields (à la dimensional deconstruction) and further spontaneously broken by an adjoint scalar (à la triplet Higgs mechanism). In this multivector boson theory, we find the solution for the monopole whose mass is MN~(4πv/g)N+1, where g is the common gauge coupling constant and v is the vacuum expectation value of the triplet Higgs field, by using a variational method with the simplest set of test functions.

Black-holes-hedgehogs in the false vacuum and a new physics beyond the Standard Model

In the present talk, we consider the existence of the two degenerate universal vacua: a) the first Electroweak vacuum at v = 246 GeV - “true vacuum”, and b) the second Planck scale “false vacuum” at v2 ∼ 1018 GeV. In these vacua, we investigated the different topological defects. The main aim of this paper is an investigation of the hedgehog’s configurations as defects of the false vacuum. In the framework of the f(R) gravity, suggested by authors in their Gravi-Weak Unification model, we obtained a black hole solution, which corresponds to a “hedgehog” - global monopole, “swallowed” by a black-hole with mass ∼ 1019 GeV. These black-holes form a lattice-like structure of the vacuum at the Planck scale. Considering the results of the hedgehog lattice theory in the framework of the SU(2) Yang-Mills gauge-invariant theory with hedgehogs in the Wilson loops, we have used the critical value of temperature for the hedgehog’s confinement phase. This result gave us the possibility to conclude that there exist triplet Higgs fields which can contribute to the SM at the energy scale ≃ 104 ∼ 105 GeV. Showing a new physics at the scale 10÷100 TeV, these triplet Higgs particles can provide the stability of the EW-vacuum of the SM.

Higgs phenomenology in the minimalSU(3)L×U(1)Xmodel

We investigate the phenomenology of a model based on the $SU(3)_c\times SU(3)_L\times U(1)_X$ gauge theory, the so-called 331 model. In particular, we focus on the Higgs sector of the model which is composed of three $SU(3)_L$ triplet Higgs fields, and this corresponds to the minimal form to realize phenomenologically acceptable scenario. After the spontaneous symmetry breaking $SU(3)_L\times U(1)_X\to SU(2)_L\times U(1)_Y$, our Higgs sector effectively becomes that with two $SU(2)_L$ doublet scalar fields, in which the first and the second generation quarks couple to the different Higgs doublet from that couples to the third generation quarks. This structure causes the flavour changing neutral current mediated by Higgs bosons at the tree level. By taking an alignment limit of the mass matrix for the CP-even Higgs bosons, which is naturally realized in the case with the breaking scale of $SU(3)_L\times U(1)_X$ to be much larger than that of $SU(2)_L\times U(1)_Y$, we can avoid current constraints from flavour experiments such as the $B^0$-$\bar{B}^0$ mixing even for the Higgs bosons masses being ${\cal O}(100)$ GeV. In this allowed parameter space, we clarify that a characteristic deviation in quark Yukawa couplings of the standard model-like Higgs boson is predicted, which has a different pattern from that seen in two Higgs doublet models with a softly-broken $Z_2$ symmetry. We also find that the flavour violating decay modes of the extra Higgs boson, e.g., $H/A \to tc$ and $H^\pm \to ts$ can be dominant, and they yield the important signature to distinguish our model from the two Higgs doublet models.

Two-photon decay of the Higgs bosons in a supersymmetric model with aCP-violating potential

In the supersymmetric standard model which is not minimal, the Higgs potential does not conserve CP symmetry generally. Assuming that there exists an SU(2)-triplet Higgs field, we discuss resultant CP-violating effects on the Higgs bosons. The experimentally observed Higgs boson, which should be CP-even in the standard model, could decay into two photons of CP-odd polarization state non-negligibly. For the second lightest Higgs boson, in sizable region of parameter space, the dominant decay modes are different from those expected by the standard model. The two-photon decay could yield both even and odd CP final states at a ratio of oder of unity.

Triplet seesaw model: from inflation to asymmetric dark matter and leptogenesis

The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. Likewise, the nature of the inflaton is unknown as well. We investigate the triplet seesaw model in an unified picture. At high energy scale, we consider Higgs inflation driven by an admixture of standard model and triplet Higgs fields, both coupled non–minimally to gravity. At intermediate and low energies we investigate vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis–via–leptogenesis induced by the decay of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type–II seesaw. We then apply Bayesian statistics to infer the model parameters giving rise to the observed baryon asymmetry and DM density, compatibly with inflationary and DM direct detection constraints, updated with the CRESST–II excess, the new XENON100 data release and KIMS exclusion limit.

Radiative generation of lepton masses

We propose a new mechanism where both Dirac masses for the charged-leptons and Majorana masses for neutrinos are generated via quantum levels. The charged-lepton masses are given by the vacuum expectation values (VEVs) of the Higgs doublet field and that of a triplet field. On the other hand, neutrino masses are generated by two VEVs of triplet Higgs fields. As a result, the hierarchy between the masses for charged-leptons and neutrinos can be explained by the triplet VEVs which have to be much smaller than the doublet VEV due to the constraint from the electroweak rho parameter. We construct a concrete model to realize this mechanism with discrete $\mathbb{Z}_2$ and $\mathbb{Z}_4$ symmetries, in which masses for neutrinos and those for the muon and electron are generated at the one-loop level. As a bonus in our model, the deviation in the measured muon $g-2$ from the standard model prediction can be explained by contributions of extra particle loops. Besides, the lightest $\mathbb{Z}_2$-odd neutral particle can be a dark matter candidate. The collider phenomenology is also discussed, especially focusing on doubly-charged scalar bosons which are necessary to introduce to occur our mechanism.

Brane realization of Nambu monopoles and electroweak strings

In the standard model, the electroweak Z-string can end on a Nambu monopole, whose mass is calculated to be 689 GeV from the current precise experimental data assuming the new particle with mass 125 GeV to be the Higgs boson. We study an extension of the standard model with additional singlet and triplet Higgs fields in the framework of N=1 supersymmetric field theory by using a D-brane configuration in type IIA string theory. We construct a D-brane configuration describing the electroweak symmetry breaking, and find a single D2-brane configuration describing a Z-string and a Nambu monopole attached by a Z-string in the standard model without an adjoint Higgs field. We further find a single D2-brane configuration describing a composite of a 't Hooft-Polyakov monopole and a Nambu monopole attached by a Z-string in an extended standard model with an adjoint Higgs field. We compute the binding energy of the 't Hooft-Polyakov and Nambu monopoles by solving a minimal surface area of a D2-brane.

Minimal supersymmetric left–right model with automatic R-parity

We revisit the minimal supersymmetric left–right model with B − L = 2 triplet Higgs fields and show that a self-consistent picture emerges with automatic R-parity conservation even in the absence of higher-dimensional operators. By computing the effective potential for the Higgs system including heavy Majorana neutrino Yukawa couplings we show that the global minimum of the model can lie in the charge and R-parity conserving domain. The model provides natural solutions to the SUSY phase problem and the strong CP problem and makes several interesting predictions. Quark mixing angles arise only after radiative corrections from the lepton sector are taken into account. A pair of doubly charged Higgs fields remain light below TeV with one field acquiring its mass entirely via renormalization group corrections. We find this mass to be not much above the Bino mass. In the supergravity framework for SUSY breaking, we also find similar upper limits on the stau masses. Natural solutions to the μ problem and the SUSY CP problem entails light SU ( 2 ) L triplet Higgs fields, leading to rich collider phenomenology.

A model of electroweak-scale right-handed neutrino mass

If neutrino masses are realized through the see-saw mechanism, can the right-handed neutrinos be produced and detected at present and future colliders? The answer is negative in the most popular see-saw scenarios for the simple reason that they are too heavy in these models. However, a simple extension of the Standard Model (SM) particle content, including mirror fermions, two SU(2)L triplet and one singlet Higgs fields, leads to a scenario in which the see-saw mechanism is realized with the Majorana mass MR of the right-handed neutrino being of the order of the electroweak scale or smaller. A custodial SU(2) symmetry arising from the two triplet Higgs fields ensures that ρ=1 at tree level even when their vacuum expectation values (VEV) which determine the value of MR, can be as large as the electroweak scale. MR is found to obey the bound MZ2⩽MR<246 GeV which makes it accessible experimentally (Tevatron, LHC or ILC) since, in our scenario, νR's can couple directly to the Standard Model (SM) gauge bosons.

Affleck–Dine leptogenesis with triplet Higgs

We study an extension of the supersymmetric standard model including a pair of electroweak triplet Higgs $\Delta$ and ${\bar \Delta}$. The neutrinos acquire Majorana masses mediated by these triplet Higgs fields rather than the right-handed neutrinos. The successful leptogenesis for baryogenesis can be realized after the inflation through the Affleck-Dine mechanism on a flat manifold consisting of $\Delta$, ${\bar \Delta}$, ${\tilde e}^c$ (anti-slepton), even if the triplet Higgs mass $M_\Delta$ is much larger than the gravitino mass $m_{3/2} \sim 10^3 {\rm GeV}$. Specifically, due to the effects of the potential terms provided with the superpotential terms $M_\Delta {\bar \Delta} \Delta$, $(\lambda_{L /} / 2M) {\bar \Delta} {\bar \Delta} e^c e^c$, $(\lambda_\Delta / 2M) {\bar \Delta} \Delta {\bar \Delta} \Delta$ ($\lambda_{L /} / \lambda_\Delta \sim 0.3 - 3$), the phases of $\Delta$, ${\bar \Delta}$, ${\tilde e}^c$ are rotated at the time with the Hubble parameter $H \sim M_\Delta$, producing generally the asymmetry with fraction $\epsilon_L \sim 0.1$. If $M_\Delta$ is large enough, this early leptogenesis can be completed before the thermal effects take place.

Fine-tuning problem in left-right symmetric model with triplet Higgs field and Sogami&apos;s generalized covariant derivative method(Topics related with Higgs Boson)

Fine-tuning problem in left-right symmetric model with triplet Higgs field and Sogami&apos;s generalized covariant derivative method(Topics related with Higgs Boson)

A partial unification model in non-commutative geometry

We consider the construction of SU (2) L ⊗ SU (2) R ⊗ SU (4) partial unification models as an example of phenomenologically acceptable unification models in the absence of supersymmetry in non-commutative geometry. We exploit the Chamseddine, Felder and Fröhlich generalization of the Connes and Lott model building prescription. By introducing a bi-module structure and appropriate permutation symmetries we construct a model with triplet Higgs fields in the SU (2) sectors and spontaneous breaking of SU (4).

Chargino-neutralino production in $$p\bar p$$ -collisions for the left-right supersymmetric model

An extension of the supersymmetric standard model to the supersymmetric SU(2)$\sb{\rm L}$ x SU(2)$\sb{\rm R}$ x U(1)$\sb{\rm B-L}$ model is considered. The gauge group contains bi-doublet and triplet Higgs fields. In this work we have considered chargino (charged gauginos mixed with higgsinos) and neutralino (neutral gauginos mixed with higgsinos) eigenstates for the left-right supersymmetric (L-R SUSY) model. After mixing, in the minimal supersymmetric model (MSSM), there are two charginos and four neutralinos. In the L-R supersymmetric model, in addition to four charginos there are three neutralinos generated from the first symmetry breaking, and four neutralinos generates from the second symmetry breaking. The mixings are in general model dependent. In the minimal SUSY and L-R SUSY models, these mixings can be parameterized in terms of a few parameters. We find analytical expressions and numerical solutions for the mass eigenstates with some restrictions on the L-R parameters. We also investigate the possibility of detecting chargino and neutralino production in pp-collisions at CDF, namely $\rm p\bar{p}\to W\sbsp{L,R}{-} + X\to\ \sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X.$ The expressions for these inclusive cross-sections are solved numerically, using parton model distributions. We have used $\rm \tilde{M}\sb\chi -= 45\ GeV,$ tan$\beta$ = 1 and a lower bound on the lightest supersymmetric particle (LSP) mass, $\tilde\chi$ = 14 GeV. Finally we take $\rm M\sb{WR}\ge 300$ GeV for $\rm g\simeq g\sb{L}\simeq g\sb{R}.$ In the pp-center of mass frame we find the cross sections are: $\rm \sigma\sb{L}(p\bar{p}\to W\sbsp{L}{-} + X\to\sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X)\approx0.11$ nb, and $\rm \sigma\sb{R}(p\bar{p}\to W\sbsp{R}{-} + X\to\sbsp{\chi\sb{j}}{\sim\sb-}\sbsp{\chi\sb{i}}{\sim0} + X)\approx4.6$ pb, and thus $\rm \sigma\sb{L}\ge24\sigma\sb{R}$ at $\sqrt{\rm s}$ = 1.8 TeV. Cross sections are also given for larger values of the center of mass energy $\sqrt{\rm s}$ up to those available at the SSC. The results are compared with the prompt-lepton background of the $\rm W\sbsp{L,R}{-}$ decays from $\rm p\bar{p}\to W\sbsp{L,R}{-} + X\to\ell\sp-\nu\sb{\ell L,R} + X.$ Both decays for $\rm W\sbsp{L,R}{-}$-bosons show Jacobian peaks for $\rm p\sb{T} = \sqrt{\{s}}/2\simeq M\sb{WL}/2\simeq40$ GeV $\rm (p\sb{T}\simeq 150$ GeV for M$\sb{\rm WR})$ at $\theta=90\sp\circ.$ Furthermore the chargino signature unlike the prompt-lepton background is symmetric under the Jacobian peak. We also exhibit the dependence of the angular distribution of the chargino on the c.m angle $\theta$ for $\rm p\sb{T} = 40$ GeV, 150 GeV at $\sqrt{\rm s} = 1.8$ TeV.

Triplet Higgs and dynamical electroweak symmetry breaking

Within the composite t R t L model for the doublet Higgs field in the Weinberg-Salam theory, a generalization involving a complex, triplet Higgs-type field discussed originally by Ross and Veltman, emerges naturally as the effective lagrangian describing the Higgs sector at low energies. The new, triplet Higgs field can be interpreted as a t R t L t R t L composite. The parameters in the model are, however, almost completely determined by the infrared fixed point of the renormalization group equations. Given the typical prediction for the top quark mass, m t =220–230 GeV, the most recent LEP data leads to a ratio of the vacuum expectation values of the Higgs triplet versus doublet of the magnitude 0.07±0.02.