Electroweak scale active right-handed neutrinos such as those proposed in a recent model necessitate the enlargement of the SM Higgs sector to include Higgs triplets with doubly charged scalars. The search for and constraints on such Higgs sector has implications not only on the nature of the electroweak symmetry breaking but also on the possibility of testing the seesaw mechanism at colliders such as the LHC and the ILC.
A model of electroweak-scale right-handed neutrino (\ewnur) model was constructed five years ago in which the right-handed neutrinos are members of mirror fermion weak doublets and where the Majorana masses of the right-handed neutrinos are found to be {\em naturally} of the order of the electroweak scale. These features facilitate their searches at the LHC through signals such as like-sign dilepton events. This model contains, in addition to the mirror quarks and leptons, extra scalars transforming as weak triplets. In this paper, we study the constraints imposed on these additional particles…
We present the Higgs mechanism in the context of the EW-scale $ν_R$ model in which electroweak symmetry is dynamically broken by condensates of mirror quark and right-handed neutrino through the exchange of one fundamental Higgs doublet and one fundamental Higgs triplet, respectively. The formation of these condensates is dynamically investigated by using the Schwinger-Dyson approach. The occurrence of these condensates will give rise to the rich Higgs spectrum. In addition, the VEVs of Higgs fields is also discussed in this dynamical phenomenon.
The lepton number violating interactions generated by the light Majorana neutrinos can erase the primordial baryon asymmetry of the universe during the electroweak phase transition. The Majorana masses of the left-handed neutrinos are constrained to avoid this problem. These constraints do not depend on the $(B-L)$ symmetry breaking mechanism.
The lepton flavor violating process μ \rightarrow eγ has been previously studied in a model of electroweak-scale right-handed neutrinos. We have calculated the decay amplitude in unitarity gauge [1] and Rξ gauge [2]. In this paper, we calculate the anomalous magnetic moment of μ in Rξ gauge.
We discuss leptogenesis in the context of type-II seesaw in the case in which in addition to the scalar electroweak triplet decays the lepton asymmetry is also induced by right-handed neutrino decays (mild hierarchical scenarios). We show that within this setup, depending on the relative sizes of the relevant parameters, one can identify three classes of generic models, each one with its own consequences for leptogenesis.
The possibility of constructing a model in which right-handed neutrinos have electroweak-scale masses as well as being {\em non-sterile} was espoused in Ref. 1. In this talk, I will review the ideas and results of Ref. 1 and discuss its implications for colliders such as the Tevatron, LHC and ILC.
Leptogenesis appears to be a viable alternative to account for the baryon asymmetry of the universe through baryogenesis. In this context, we consider a scenario in which the standard model is extended with $S_3$ and $Z_2$ symmetry in addition to the two scalar triplets, two scalar doublets and three right handed neutrinos. Presence of scalar triplets and right-handed neutrinos in the scenarios of both type-I and type-II seesaw framework provide a different leptogenesis option and can help us to understand the matter-antimatter asymmetry with simple $S_3$ symmetry. We discuss the neutrino phen…
Can, and under which conditions, the 125-\gev SM-like scalar with the signal strengths for its decays into $W^{+}W^{-}$, $ZZ$, $γγ$, $b \bar{b}$ and $τ\barτ$ being consistent with experiments be accommodated in models that go beyond the Standard Model? Is it truly what it appears to be, namely the SM Higgs boson, or could it be quite different? A minimal extension of the original electroweak-scale right-handed neutrino model, in which right-handed neutrinos naturally obtain electroweak-scale masses, shows a scalar spectrum which includes either the 125-\gev SM-like scalar or a scalar which is …
A new weak-isospin triplet of scalar bosons is introduced to the Standard Model in order to ensure the electroweak symmetry for a conjectured new weak coupling between a hidden sector of the Universe, responsible for cold dark matter, and the Standard-Model sector (involving now the new triplet). The considered coupling may be called "electroweak portal" to the structure of hidden sector. After spontaneously breaking the electroweak symmetry by the Standard-Model Higgs mechanism, it includes the so called "photonic portal" introduced by us previously.
A version of the $\mbox{SU(3)}_L\otimes \mbox{U(1)}_N$ electroweak theory in which there are right-handed neutrino currents is reconsidered in detail. We argue that in order to have a result consistent with low-energy one, the right-handed neutrino component must be treated as correction instead of an equivalent spin state. The data from the $Z$-decay allow us to fix the limit for $ϕ$ as $-0.00285 \leq ϕ\leq 0.00018$. From the neutrino neutral current scattering, we estimate a bound for the new neutral gauge boson $Z^2$ mass in the range of 400 GeV. A bound for the new charged and neutral (non…
We explore in detail the Higgs phenomenology that results in a model where right-handed neutrinos have a mass scale of the order of the electroweak scale. In this model all scales arise from spontaneous symmetry breaking, and this is achieved with a Higgs sector that includes an extra Higgs singlet in addition to the standard model Higgs doublet. The scalar spectrum includes two neutral CP-even states ($h$ and $H$ with $m_{h} < m_{H}$)and a neutral CP-odd state ($σ$) that can be identified as a pseudo-Majoron. The parameter of the Higgs potential are constrained using a perturbativity criteria…
We compute the electroweak S and T parameters induced by SU(2)_L triplet scalars up to one-loop order. We consider the most general renormalizable potential for a triplet and the Standard Model Higgs doublet. Our calculation is performed by integrating out the triplet at the one-loop level and also includes the one-loop renormalization group running. Effective field theory framework allows us to work in the phase with unbroken SU(2)_L x U(1)_Y symmetry. Both S and T parameters exhibit decoupling when all dimensionful parameters are large while keeping dimensionless ratios fixed. We use bounds …
We present two different models with electroweak scale right-handed neutrinos. One of the models is created under the constraint that any addition to the Standard Model must not introduce new higher scales. The model contains right-handed neutrinos with electroweak scale masses and a lepton number violating singlet scalar field. The scalar phenomenology is also presented. The second model is a triplet Higgs model where again the right-handed neutrinos have electroweak scale masses. In this case the model has a rich scalar phenomenology and in particular we present the analysis involving the do…
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 $M_R$ of the right-handed neutrino being of the order of the electroweak scale or smal…
We consider an $SU(3)_c \otimes SU(2)_L \otimes SU(2)_R \otimes U(1)_{B-L}$ left-right symmetric model with three Higgs scalars including an $SU(2)_L$ doublet, an $SU(2)_R$ doublet and an $SU(2)_L \otimes SU(2)_R$ bidoublet. In addition to usual SU(2)-doublet fermions, our model contains SU(2)-triplet fermions with Majorana masses. The neutral components of the left-handed triplets can contribute a canonical seesaw while the neutral components of the right-handed triplets associated with the right-handed neutrinos can contribute a double/inverse-type seesaw. Our model can be embedded into an S…
The existence of certain TeV suppressed higher-dimension operators may open up new decay channels for the Higgs boson to decay into lighter right-handed neutrinos. These channels may dominate over all other channels if the Higgs boson is light. For a Higgs boson mass larger than $2 m_W$ the new decays are subdominant yet still of interest. The right-handed neutrinos have macroscopic decay lengths and decay mostly into final states containing leptons and quarks. A distinguishing collider signature of this scenario is a pair of displaced vertices violating lepton number. A general operator analy…
We show that, for all values of $Tan β$ and the light right-handed stop mass for which the electroweak phase transition is strong enough to avoid washout following electroweak baryogenesis, the electroweak vacuum is stable over the lifetime of the observed Universe. Cosmological stability of the electroweak vacuum is violated only if the light right-handed stop is lighter than 100-115GeV.
We propose an alternative mechanism for leptogenesis at the electroweak scale, through the decays of a left-handed sneutrino. This scenario may be realized in supersymmetric models with non-zero Majorana masses for the neutrino superfield that lead to mixing and mass splitting between the left-handed sneutrino and the corresponding antisneutrino. Soft supersymmetry breaking provides new sources of CP violation in sneutrino-antisneutrino mixing that can generate a lepton asymmetry in decays of the left-handed sneutrino. We show how the three Sakharov conditions for generating the observed baryo…
The neutral component of a real pseudoscalar electroweak (EW) triplet can produce a diphoton excess at 750 GeV, if it is somewhat mixed with an EW singlet pseudoscalar. This triplet-singlet mixing allows for greater freedom in the diboson branching ratios than the singlet-only case, but it is still possible to probe the parameter space extensively with 300 fb$^{-1}$. The charged component of the triplet is pair-produced at the LHC, which results in a striking signal in the form of a pair of $Wγ$ resonances with an irreducible rate of 0.27 fb. Other signatures include multiboson final states fr…
During a large period of time, the anomalous baryon number violating interactions are in equilibrium, when the $(B+L)$ asymmetry is washed out. If there is any lepton number violation during this period, that will also erase the $(B-L)$ asymmetry. As a result, survival of the baryon asymmetry of the universe pose strong constraints on lepton number violating interactions. We review here the constraints on the left-handed Majorana neutrino masses arising from this survival requirement of the baryon asymmetry of the universe. We then briefly review models of leptogenesis, where lepton number vio…
It was shown recently that the original SU(5) theory of Georgi and Glashow, augmented with an adjoint fermionic multiplet 24_F, can be made compatible both with neutrino masses and gauge coupling unification. In particular, the model predicts that either electroweak-triplet states are light, within the reach of the Large Hadron Collider (LHC), or proton decay will become accessible at the next generation of megaton-scale facilities. In this paper, we present the computation of the correlation function between the electroweak-triplet masses and the unification scale at the next-to-next-to-leadi…
We study the production of scalar leptoquarks at IceCube, in particular, a particle transforming as a triplet under the weak interaction. The existence of electroweak-triplet scalars is highly motivated by models of grand unification and also within radiative seesaw models for neutrino mass generation. In our framework, we extend the Standard Model by a single colored electroweak-triplet scalar leptoquark and analyze its implications on the excess of ultra-high energy neutrino events observed by the IceCube collaboration. We consider only couplings between the leptoquark to first generation le…
We consider a modification of the standard electroweak model with the third quark generation and the $τ$-lepton in vector representations of $SU(2)\otimes U(1)_Y$ electroweak symmetry. This is a new way to implement right-handed currents which are controlled by the usual Fermi constant, $G_F$, the weak mixing angle, $\sinθ_W$, and also by the right-handed mixing matrices which survive when the Lagrangian density is written in terms of the mass eigenstates. In this case there are also new CP violation phases.
The muon-to-electron conversion in nuclei like aluminum, titanium and gold is studied in the context of a class of mirror fermion model with non-sterile right-handed neutrinos having mass at the electroweak scale. At the limit of zero momentum transfer and large mirror lepton masses, we derive a simple formula to relate the conversion rate with the on-shell radiative decay rate of muon into electron. Current experimental limits (SINDRUM II) and projected sensitivities (Mu2e, COMET and PRISM) for the muon-to-electron conversion rates in various nuclei and latest limit from MEG for the radiative…
A two-component scalar DM scenario comprising an additional scalar doublet and a $Y$ = 0 scalar triplet is proposed. Key features of the ensuing dark matter phenomenology are highlighted with emphasis on inter-conversion between the two dark matter components. For suitable choices of the model parameters, we show that such inter-conversion can explain the observed relic abundance when the doublet dark matter component has mass in the \emph{desert} region while the triplet component has sub-TeV mass. This finding is important in the context of such mass regions known to predict under-abundant r…
We propose a minimal type II seesaw model by introducing only one right-handed neutrino besides the $SU(2)_{L}$ triplet Higgs to the standard model. In the usual type II seesaw models with several right-handed neutrinos, the contributions of the right-handed neutrinos and the triplet Higgs to the CP asymmetry, which stems from the decay of the lightest right-handed neutrino, are proportional to their respective contributions to the light neutrino mass matrix. However, in our minimal type II seesaw model, this CP asymmetry is just given by the one-loop vertex correction involving the triplet Hi…
We study the possibility of baryogenesis in the case of supersymmetry breaking with large mixing between the right-handed scalar charm and right-handed scalar top or right-handed scalar up and right-handed scalar top squarks resulting in one light right-handed up-type squark mass eigenstate. We argue that in this case the electroweak phase transition will be first order, and that large phases already present in the quark mass matrices can generate a baryon asymmetry of the correct magnitude without introducing any new phases specifically for this purpose. We study in detail a particular ansatz…
The possibility of creating baryon asymmetry at the electroweak phase transition in the minimal supersymmetric standard model is considered for the case when right-handed squarks are much lighter than left-handed ones. It is shown that the usual requirement v(T_c)/T_c > 1 for baryogenesis can be satisfied in a range of the parameters of the model, consistent with present experimental bounds.
Electroweak precision observables are fundamentally important for testing the standard model (SM) or its extensions. The influences to observables from new physics within the electroweak sector can be expressed in terms of oblique parameters S, T, U. The recently reported W mass excess anomaly by CDF modifies these parameters in a significant way. By performing the global fit with the CDF new W mass measurement data, we obtain $S=0.03 \pm 0.03$, $T=0.06 \pm 0.02$ and $U=0.16 \pm 0.03$ (or $S=0.14 \pm 0.03$, $T=0.24 \pm 0.02$ with $U=0$) which is significantly away from zero as SM would predict…
While an additional scalar multiplet over and above the Standard Model can lead to a strong electroweak phase transition, depending on its quantum numbers, it also potentially confronts crucial constraints from theory and experiments. Should there exist more than one copy of such a multiplet, it is possible to predict that number from the requirements of a strong electroweak phase transition and agreement with the latest constraints. We aim to probe this specific issue in this study in the context of $N$ degenerate scalar triplets governed by a global O$(N)$ symmetry. We fold in important cons…
The Georgi-Machacek model extends the standard model Higgs sector by adding two isospin triplet scalar fields and imposing global SU(2)$_R$ symmetry on them. A feature of the model is that the triplets can acquire a large vacuum expectation value without conflicting with the current experimental bound on the $ρ$ parameter. We investigate the electroweak phase transition in the Georgi-Machacek model by evaluating the finite-temperature effective potential of the Higgs sector. The electroweak phase transition can be sufficiently strong in a large parameter space when the triplets acquire a vacuu…
We propose a two component dark matter set-up by extending the Standard Model with a singlet and a hypercharge-less triplet scalars, each of them being odd under different $Z_2$ symmetries. We observe that the inter-conversion between the two dark matter components allow a viable parameter space where masses of both the dark matter candidates can be below TeV, even though their individual contribution to single component dark matter rules out any such sub-TeV dark matter. We find that a lighter mass of the neutral component of the scalar triplet, playing the role of one dark matter component, …
We extend the DFSZ invisible axion model to simultaneously explain small Dirac neutrino masses and cosmic matter-antimatter asymmetry. After the Peccei-Quinn and electroweak symmetry breaking, the effective Yukawa couplings of the Dirac neutrinos to the standard model Higgs scalar can be highly suppressed by the ratio of the vacuum expectation value of an iso-triplet Higgs scalar over the masses of some heavy gauge-singlet fermions, iso-doublet Higgs scalars or iso-triplet fermions. The iso-triplet fields can carry a zero or nonzero hypercharge. Through the decays of the heavy gauge-singlet fe…
We study the thermal leptogenesis in the scenario where the standard model is extended to include one $SU(2)_{L}$ triplet Higgs boson, in addition to three generations of the right-handed neutrinos. And in the model we introduce the coupling between the Quintessence and the right-handed neutrinos, the triplet Higgs boson, so that the light neutrino masses vary during the evolution of the universe. Assuming that the lepton number asymmetry is generated by the decays of the lightest right-handed neutrino $N_{1}$, we find the thermal leptogenesis can be characterized by four model independent par…
We present a model of neutrino masses within the framework of the EW-$ν_R$ model in which the experimentally desired form of the PMNS matrix is obtained by applying an $A_4$ symmetry to the \emph{Higgs singlet sector} responsible for the neutrino Dirac mass matrix. This mechanism naturally avoids potential conflict with the LHC data which severely constrains the Higgs sector, in particular the Higgs doublets. Moreover, by making a simple $ans\ddot{a}tz$ we extract $\mathcal{M}_l {\mathcal{M}_l}^\dagger$ for the charged lepton sector. A similar $ans\ddot{a}tz$ is proposed for the quark sector. …
The nonlinear SU(2) electroweak model is used to explain the absence of the right-handed neutrino in weak interactions. Two covariant eigenvalue constraints which affect the transformation lead to two classes of right-handed leptons, and make possible invariant mass terms without the Higgs doublet. A covariant picture of neutrinos with mass is presented. A new invariant form for the boson potentials is described in which the boson mass terms arises via the adjoint field. This model also indicates a different region of matter involving coupled leptons that are "blind" to the massless electromag…
Motivated by the null results of the BSM searches in the post-Higgs era of the LHC, our current approach is to look for new physics shifting from theory driven search strategies to signature driven ones. One possible direction might come from investigating the long-lived particles (LLPs) present in various theoretical scenarios through the newly formed Lifetime frontier. In this talk, I discuss a non-sterile right-handed neutrino model consisting of EW-scale Majorana masses, having signals with large displaced vertices arising in both the fermion and scalar sectors. The characteristic features…
We present the various leptogenesis scenarios which may occur if, in addition to the ordinary heavy right-handed neutrinos, there exists a heavy scalar SU(2)_L triplet coupled to leptons. We show that the contributions of the right-handed neutrinos and the triplet to the lepton asymmetry are proportional to their respective contributions to the neutrino mass matrix. A consequence of the triplet contribution to the lepton asymmetry is that there is no more upper bound on the neutrino masses from leptogenesis due to the fact that the neutrino mass constraints do not necessarily induce asymmetry …
We study radiative corrections to the electroweak parameters in the Higgs model with the Y=1 triplet field, which is introduced in the scenario of generating neutrino masses based on the so-called type II seesaw mechanism. In this model, the rho parameter deviates from unity at the tree level. Consequently, the electroweak sector of the model is described by the four input parameters such as $α_{\text{em}}$, $G_F$, $m_Z$ and $\sin^2θ_W$. We calculate the one loop contribution to the W boson mass as well as to the rho parameter in order to clarify the possible mass spectrum of the extra Higgs b…
We study the phenomenology of a hypercharge-zero SU(2) triplet scalar whose existence is motivated by two-step electroweak symmetry-breaking. We consider both the possibility that the triplets are stable and contribute to the dark matter density, or that they decay via mixing with the standard model Higgs boson. The former is constrained by disappearing charged track searches at the LHC and by dark matter direct detection experiments, while the latter is constrained by existing multilepton collider searches. We find that a two-step electroweak phase transition involving a stable triplet with a…
Strongly electroweak phase transition with $U(1)_{L_μ-L_τ}$ gauged non-zero hypercharge triplet
Yonsei University（延世大学）；Gaya College (A constituent unit of Magadh University, Bodh Gaya)（盖亚学院（巴德伽大学波达伽雅下属单位））；SR University（SR大学）；Asia Pacific Center for Theoretical Physics (APCTP) - Headquarters（亚太理论物理中心总部）；Shiv Nadar IoE Deemed to be University（希夫·纳德尔工程学院 deemed 大学）
We investigate a simple variant of type-II seesaw, responsible for neutrino mass generation, where the particle spectrum is extended with one singlet right-handed neutrino and an inert Higgs doublet, both odd under an additional $Z_2$ symmetry. While the role of the dark matter is played by the lightest neutral component of the inert Higgs doublet, its interaction with the Standard Model lepton doublets and the right-handed neutrino turns out to be crucial in generating the correct baryon abundance of the Universe through flavored leptogenesis from the decay of the $SU(2)_L$ scalar triplet, in…
We discuss a 331 model with three scalar triplets and neutral fermion singlets. We show that in the 331 model with right-handed neutrinos, it is possible to obtain small active neutrino masses via the double and inverse seesaw mechanisms, without the use of scalar sextets or triplets with doubly-charged Higgs. Two types of models are discussed. If we have a large Majorana mass matrix for the singlets, the spectrum of neutrinos presents light, heavy and very heavy masses. The other possibility is a small (zero) Majorana mass matrix, which leads to pseudo-Dirac (Dirac) heavy neutrinos in the TeV…
Motivated by the recent discovery of the Higgs boson at m_h = 126 GeV and also by the non-observation of superparticles at the LHC, high-scale SUSY, where the superparticles are as heavy as O(10) TeV, has been recently proposed. We study lepton-flavor violations (LFVs) in the high-scale SUSY with right-handed neutrinos. Even if the slepton masses are of O(10) TeV, the renormalization group (RG) effects on the slepton mass-squared matrix may induce large enough LFVs which are within the reach of future LFV experiments. We also discuss the implication of the right-handed neutrinos on the electro…
The standard model can be interpreted as the leading order of a Low-Energy Effective Theory (LEET) invariant under a higher non linearly realized symmetry $S_{nat}\supset SU(2)_W \times U(1)_Y$ equipped with a systematic power counting. Within the minimal version of this ``not quite decoupling'' LEET, the dominant non-standard effect appears at next-to-leading order (NLO) and is a modification of the couplings of fermions to W and Z. In particular, the coupling of right-handed quarks to Z is modified and a direct coupling of right-handed quarks to W emerges. Charged right-handed lepton current…
A simple and economical extension of the minimal standard electroweak gauge model (without right-handed neutrinos) by the addition of two heavy Higgs scalar triplets would have two significant advantages. \underline {Naturally} small Majorana neutrino masses would become possible, as well as leptogenesis in the early universe which gets converted at the electroweak phase transition into the present observed baryon asymmetry.
Electroweak precision data has been extensively used to constrain models containing physics beyond that of the Standard Model. When the model contains Higgs scalars in representations other than SU(2) singlets or doublets, and hence rho not equal to one at tree level, a correct renormalization scheme requires more inputs than the three needed for the Standard Model. We discuss the connection between the renormalization of models with Higgs triplets and the decoupling properties of the models as the mass scale for the scalar triplet field becomes much larger than the electroweak scale. The requ…
The presence of right-handed neutrinos in the type I seesaw mechanism may lead to significant corrections to the RG evolution of the Higgs self-coupling. Compared to the Standard Model case, the Higgs mass window can become narrower, and the cutoff scale become lower. Naively, these effects decrease with decreasing right-handed neutrino mass. However, we point out that the unknown Dirac Yukawa matrix may impact the vacuum stability constraints even in the low scale seesaw case not far away from the electroweak scale, hence much below the canonical seesaw scale of 10^15 GeV. This includes situa…
The aim of the thesis is to study models of the electroweak symmetry breaking caused by dynamically generated masses of quarks and leptons. (1) We perform the basic analysis whether the main underlying idea, that the masses of only known fermions can provide the electroweak symmetry breaking, is actually feasible. For that we elaborate a two-composite-Higgs-doublet model of the top-quark and neutrino condensation. The model suggests rather large number, $\mathcal{O}(100)$, of right-handed neutrinos. (2) We analyze the model of strong Yukawa dynamics where the dynamical fermion mass generation …
We analyse the minima of scalar potentials for multi-Higgs models where the scalars are arranged as either one triplet or two triplets of the discrete symmetries $A_4$, $S_4$, $Δ(27)$, $Δ(54)$, as well as $Δ(3n^2)$ and $Δ(6n^2)$ with $n>3$. The results should be useful for both multi-Higgs models involving electroweak doublets and multi-flavon models involving electroweak singlets, where in both cases the fields transform as triplets under some non-Abelian discrete symmetry.
We discuss the phenomenology of the most general effective Lagrangian, up to operators of dimension 5, build with standard model fields and interactions including right-handed neutrinos. In particular we find there is a dimension 5 electroweak moment operator of right-handed neutrinos, not discussed previously in the literature, which could have interesting phenomenological consequences.
In this article we examine the prospect of first order phase transition with a Y=0 real $SU(2)$ triplet extension of the Standard Model, which remains odd under $Z_2$, considering the observed Higgs boson mass, perturbative unitarity, dark matter constraints, etc. Especially we investigate the role of Higgs-triplet quartic coupling considering one- and two-loop beta functions and compare the results with the complex singlet extension case. It is observed that at the one-loop level, no solution can be found for both, demanding the Planck scale perturbativity. However, for a much lower scale of …
The construction of an effective 3D theory at high temperatures for the MSSM as a model of electroweak baryogenesis is discussed. The analysis for a single light scalar field shows, that given the experimental constraints, there is no value of the Higgs mass for which a sufficiently first-order phase transition is obtained. A precise determination of the 3D parameters of the effective theory for the case of a light right-handed stop allows us to obtain an upper bound on the masses of the lightest Higgs and right-handed stop using the two-loop effective potential. A two-stage phase transition p…
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 {\em 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 {\em non-sterile} whose electroweak-scale Majorana ma…
