We present new results on the calculation of the dark matter relic abundance within the Higgs induced right-handed (RH) neutrino mixing model, solving the associated density matrix equation. For a benchmark value of the dark matter mass $M_{\rm DM} = 220\,{\rm TeV}$, we show the evolution of the abundance and how this depends on reheat temperature, dark matter lifetime and source RH neutrino mass $M_{\rm S}$, with the assumption $M_{\rm S} < M_{\rm DM}$. We compare the results with those obtained within the Landau-Zener approximation, showing that the latter largely overestimates the final abundance giving some analytical insight. However, we also notice that since in the density matrix formalism the production is non-resonant, this allows source RH neutrino masses below the W boson mass, making dark matter more stable at large mass values. This opens an allowed region for initial vanishing source RH neutrino abundance. For example, for $M_{\rm S} \gtrsim 1\,{\rm GeV}$, we find $M_{\rm DM}\gtrsim 20\,{\rm PeV}$. Otherwise, for $M_{\rm S} > M_W\sim 100\,{\rm GeV}$, one has to assume a thermalisation of the source RH neutrinos prior to the freeze-in of the dark matter abundance. This results into a large allowed range for $M_{\rm DM}$, depending on $M_{\rm S}$. For example, imposing $M_{\rm S} \gtrsim 300\,{\rm GeV}$, allowing also successful leptogenesis, we find $0.5 \lesssim M_{\rm DM}/{\rm TeV} \lesssim 500$. We also discuss in detail leptogenesis with two quasi-degenerate RH neutrinos, showing a case when observed dark matter abundance and matter-antimatter asymmetry are simultaneously reproduced. Finally, we comment on how an initial thermal source RH neutrino abundance can be justified and on how our results suggest that also the interesting case where $M_{\rm DM} < M_{\rm S}$, embeddable in usual high scale two RH neutrino seesaw models, might be viable.
We investigate the possibility of Higgs inflation with an extended standard model by right-handed neutrinos and scalar dark matter. We find that the masses of the dark matter and one of the right-handed neutrinos should stand around TeV and $10^{-14}$ GeV scale respectively even if the magnitude of tensor-to-scalar ratio indicates sufficiently small value.
In order to have massive neutrinos, the right-handed neutrino/sneutrino superfield ($N$) need to be introduced in supersymmetry. In the framework of NMSSM (the MSSM with a singlet $S$) such an extension will dynamically lead to a TeV-scale Majorana mass for the right-handed neutrino through the $SNN$ coupling when $S$ develops a vev (the free Majorana mass term is forbidden by the assumed $Z_3$ symmetry). Also, through the couplings $SNN$ and $SH_uH_d$, the SM-like Higgs boson (a mixture of $H_u$, $H_d$ and $S$) can naturally couple with the right-handed neutrino/sneutrino. As a result, the Te…
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.
Relic abundance of dark matter is investigated in the framework of universal extra dimension models with right-handed neutrinos. These models are free from the serious Kaluza-Klein (KK) graviton problem that the original universal extra dimension model has. The first KK particle of the right-handed neutrino is a candidate for dark matter in this framework, and its relic abundance is determined by three processes, (1) the decay of the KK photon into the first KK right-handed neutrino in the late universe, (2) production of the first KK right-handed neutrino from the thermal bath in the early un…
Recently, it has been argued that in the supersymmetric extension of the seesaw-extended Standard Model, heavy right-handed neutrinos and sneutrinos may give corrections as large as a few GeV to the mass of the lightest neutral CP-even Higgs boson, even if the soft supersymmetry-breaking parameters are of order the electroweak scale. The presence of such large corrections would render precise Higgs masses incalculable from measurable low-energy parameters. We show that this is not the case: decoupling is preserved in the appropriate sense and right-handed (s)neutrinos, if they exist, have negl…
We investigate the possibility that dark matter could be made from CP-even and CP- odd Higgs bosons in the SU(3)_C X SU(3)_L X U(1)_N (3-3-1) model with right-handed neutrinos. This self-interacting dark matters are stable without imposing of new symmetry and should be weak-interacting.
The contribution of the charged right-handed higgsino fields to the chargino mass spectrum in the context of the Left-Right Supersymmetric Model is studied. Analytical expressions for the chargino masses assuming arbitrary CP-violating phases are given. Also, the corresponding inverse parameter problem is studied. Analytical disentangling of some relevant parameters is presented. A general inversion algorithm, based on suitable measurement of cross-section type observables associated to chargino pair production in electron positron annihilation, is proposed.
The models based on ${SU}(3)_C\otimes {SU}(3)_L \otimes {U}(1)_X$ gauge group (3-3-1) contain new Higgs bosons and one of them is the SM-like Higgs boson $h$. Production of this Higgs boson at $p p$ colliders in the framework of 3-3-1 model with right-handed neutrinos is calculated. We found that the contribution of the real $Z^\prime$ to the process $pp\to hZ$ is nearly 60 fb if $M_{Z^\prime}$ is about 1 TeV. The decay width and the branching ratios of the $Z'$ extra neutral gauge boson are systematically discussed.
The existence of neutrino masses strongly suggests that right-handed neutrinos exist, but the data do not favor any particular scale for the Majorana mass parameters. Here I explore the possibility that these particles exist at the electroweak scale along with additional new physics at the TeV scale . Higher dimension operators involving right-handed neutrinos and the Higgs boson can introduce new decay modes of the Higgs boson, significantly modifying its phenomenology if it is light. With minimal flavor violation the Higgs boson cascade decays to 6 particles containing two highly displaced v…
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…
In order to meet the requirement of BBN, the right handed neutrino is added to the singlet Higgs sector in the GNMSSM. The spectrum and Feynman rules are calculated. the dark matter phenomenology is also studied. In case of $ł\sim 0$, the singlet sector can give perfect explanation of relic abundance of dark matter and small cosmological structure simulations. The BBN constraints on the light mediator can be easily solved by decaying to the right handed neutrino. When the $ł_N$ is at the order of $\mathcal{O}(0.1)$, the mass of the mediator can be constrained to several MeV
We examine the charged boson and right-handed neutrino contribution to the muon g-2 anomaly in the twin Higgs models with the joint constraints of the Higgs global fit data, the precision electroweak data, the leptonic flavor changing decay μ\to eγ, and the mass requirement of the heavy gauge bosons. It comes out with the conclusion that some parameters such as the coupling of charged Higgs to the lepton y_μ, the top Yukawa y_t, and the heavy gauge boson coupling to the lepton V_μare constrained roughly in the range of 0.12\lesssim y_μ\lesssim 0.4, 0.4\lesssim y_t\lesssim 0.9, and 0.47\lesssim…
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 equilibration of the right-helicity states $ν_+$ of light Dirac-neutrinos is discussed. I point out that the $ν_+$ production rate is enhanced by weak gauge boson pole effects so that the right-helicity component of $ν_τ$ is brought into equilibrium at $T\simeq 10$ GeV independently of the initial abundance, provided $m_{ν_τ}\gsim 10$ keV. Neutrino spin flip in primordial magnetic fields and the resulting bound on $μ_ν$ is also discussed.
In this paper we discuss the consequences of including a new heavy right-handed neutrino singlet $N_R$ in the littlest Higgs model. This new state is not connected with the light neutrinos {\it via} the seesaw mechanism. A very interesting property of this extended model is the full coupling of the new neutral gauge boson $A_H$ to $N_R$, giving large total cross sections and suggesting a wide range of experimental search for the $N_R$ at the p p collider CERN-LHC and future electron-positron collider ILC.
R-parity violation modifies the phenomenology of supersymmetric models considerably. We study a version of NMSSM, which contains right-handed neutrinos and in which spontaneous R-parity violation is possible. We study the ensuing effects of spontaneous breaking to the Higgs decay modes, taking into account the measured mass of the Higgs boson and experimental constraints, including rare decays. We find that a possible light scalar, dominantly a sneutrino, helps to increase the Standard Model (SM) Higgs-like scalar mass to the measured value. At the same time, a lighter stop than in the MSSM is…
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…
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…
In models with large extra dimensions and TeV scale quantum gravity, small (Dirac) neutrino masses can be obtained naturally if the right-handed neutrino propagates in the extra dimensions. In this scenario, with 2 Higgs doublets, we show that the decay of charged Higgs into {\em left-handed} charged lepton (say τ) and right-handed neutrino can be significantly enhanced, with O(1) branching ratio, due to the large number of Kaluza-Klein states of the right-handed neutrino. Since τ's from the standard decay of charged Higgs are {\em right-handed}, the above novel charged Higgs decay can provide…
We study parameters of an extension of the Standard Model. The neutrino sector is enlarged by one right-handed singlet field, allowing for the seesaw mechanism type-I, and the Higgs sector contains one additional doublet, which contributes to light neutrino masses through one-loop radiative corrections. Employing an approximation for the effective light neutrino mass matrix we express the masses of the light neutrinos analytically, allowing us to parametrize the Yukawa couplings to neutrinos by the experimental measurements on the neutrino sector and only two free parameters. We focus on a CP-…
This work deals with right handed sneutrino as thermal cold dark matter candidate. This scalar emerges in a supersymmetric version of $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ gauge model where right handed neutrinos are a natural component of leptonic chiral scalar supermultiplets. We first consider the issue of a $125$~GeV Higgs boson mass in this model, showing that constraints on stop mass and trilinear soft coupling are considerably alleviated compared to MSSM. Then we investigate the region of parameter space that is consistent with right handed sneutrino as thermal cold dark matter, unde…
We propose a class of the two Higgs doublet Standard models (SMs) with a SM singlet and a class of supersymmetric SMs with two pairs of Higgs doublets, where the right-handed up/charm quarks and the right-handed top quark have different quantum numbers under extra discrete symmetries. Thus, the right-handed up and charm quarks couple to one Higgs doublet field, while the right-handed top quark couples to another Higgs doublet. The quark CKM mixings can be generated from the down-type quark sector. As one of phenomenological consequences in our models, we explore whether one can accommodate the…
Low energy effects induced by heavy extra degrees of freedom are suppressed by powers of the large mass scale, thus preserving, if sufficiently heavy, the successes of the Standard Model in describing low energy phenomena. However, as is well known, heavy right-handed neutrinos may play an important role in low energy phenomenology as an explanation of the smallness of neutrino masses. We consider in this paper an extension of the Standard Model by heavy right-handed neutrinos and heavy Higgs doublets and we show, using a renormalization group approach, that this model can simultaneously provi…
In this note, we show how one can attribute the anomaly currently present in the measurement of the anomalous magnetic moment of the muon ($a_μ$) to the presence of an underlying Aligned 2-Higgs Doublet Model (A2HDM) with Right-Handed (RH) neutrinos, $ν_R$. The effects of the latter scenario are driven by one and two-loop topologies wherein a very light CP-odd neutral Higgs state ($A$) contributes significantly to $a_μ$. Over the region of parameter space of our new physics model which explains the aforementioned anomaly, also consistent with the most recent measurements of the electron anomal…
We consider an extension of the Next-to-Minimal Supersymmetric Standard Model by three right-handed neutrinos and a pair of neutrinophilic Higgs superfields. The small neutrino masses arise naturally from a small vacuum expectation value of the additional Higgs fields (hence without lepton number violation), while the lightest right-handed sneutrinos can constitute asymmetric Dark Matter. The right-handed sneutrino and baryon asymmetries are connected through equilibrium processes in the early universe, explaining the coincidence of the DM and baryon abundances. We show that particle physics a…
We analyze the vacuum stability in the inert Higgs doublet extension of the Standard Model (SM), augmented by right-handed neutrinos (RHNs) to explain neutrino masses at tree level by the seesaw mechanism. We make a comparative study of the high- and low-scale seesaw scenarios and the effect of the Dirac neutrino Yukawa couplings on the stability of the Higgs potential. Bounds on the scalar quartic couplings and Dirac Yukawa couplings are obtained from vacuum stability and perturbativity considerations. The regions corresponding to stability, metastability and instability of the electroweak va…
We consider an effective field theory framework with three standard model (SM) gauge singlet right handed neutrinos, and an additional SM gauge singlet scalar field. The framework successfully generates eV masses of the light neutrinos via seesaw mechanism, and accommodates a feebly interacting massive particle (FIMP) as dark matter candidate. Two of the gauge singlet neutrinos participate in neutrino mass generation, while the third gauge singlet neutrino is a FIMP dark matter. We explore the correlation between the $\textit{vev}$ of the gauge singlet scalar field which translates as mass of …
The relic abundance of the lightest right-handed sneutrino dark matter in supersymmetric B-L extension of the standard model is revisited. We argue that it can form a bound state through the exchange of light B-L Higgs boson and a large non-perturbative Sommerfeld effect is obtained. We emphasized that with this effect the relic abundance of right-handed sneutrino will lie within the observational limits and the right-handed sneutrino will remain a viable dark matter candidate of mass order up to 1.5 TeV.
We present a supersymmetric model of leptogenesis in which the right-handed neutrinos have weak scale masses and O(10-2-10-3) yukawa couplings. The model employs an R-symmetry at the weak scale that forces neutrino masses to be proportional to the gravitino mass. We predict that the lightest right-handed neutrino decays to a displaced Higgs and neutrino and that the NLSP is long-lived on collider scales. These could be striking signatures at the LHC if, for instance, the right-handed neutrino is produced in a cascade decay.
It is demonstrated that the light Higgs boson scenario, which the lightest Higgs mass is less than the LEP bound, mh > 114.4 GeV, is consistent with the SUSY seesaw model. With the assumptions of the universal right-handed neutrino mass and the hierarchical mass spectrum of the ordinary neutrinos, the bounds for the right-handed neutrino mass is investigated in terms of lepton flavor violating charged lepton decays. We also discuss the effect of the modification of renormalization group equations by the right-handed neutrinos on the b to s gamma process and the relic abundance of dark matter i…
We revise the limits on the FCNC higgses in manifestly left-right symmetric theories. It is shown that the combination of the Kobayashi-Maskawa CP-violation with the tree level $ΔS=2$ higgs exchange gives very large contribution to the CP-violating $ε$ parameter. It leads to the new strong constraint on the FCNC higgs mass, M>50- 100 TeV, enhanced by factor of the order $\sqrt{m_t/m_c}$. Being addressed to the supersymmetric left-right models, FCNC problem requires both right-handed scale and supersymmetric mass parameters be heavier than 50 TeV for $tanβ\sim 1$. The most relaxed case correspo…
We propose a scenario of the right-handed neutrino dark matter in the context of the minimal gauged $U(1)_{B-L}$ model by introducing an additional parity which ensures the stability of dark matter particle. The annihilation of this right-handed neutrino takes place dominantly through the s-channel Higgs boson exchange, so that this model can be called Higgs portal dark matter model. We show that the thermal relic abundance of the right-handed neutrino dark matter with help of Higgs resonance can match the observed dark matter abundance. In addition we estimate the cross section with nucleon a…
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…
The $μν$SSM is a simple supersymmetric extension of the Standard Model (SM) capable of describing neutrino physics in agreement with experiments. We perform the complete one-loop renormalization of the neutral scalar sector of the $μν$SSM with three generation of right-handed neutrinos in a mixed on-shell/$\overline{\mathrm{DR}}$ scheme. We calculate the full one-loop corrections to the neutral scalar masses of the $μν$SSM. The one-loop contributions are supplemented by available MSSM higher-order corrections. We obtain numerical results for a SM-like Higgs-boson mass consistent with experimen…
We consider the physics reach at the high luminosity LHC (HL-LHC) using the timing capability of a minimum ionizing particle (MIP) timing layer and the electromagnetic calorimeter in the CMS experiment for a simplified right-handed neutrino effective theory. In the simplified model, the lightest right-handed neutrinos are produced through higgs decay with mean decay lengths of order $\mathcal{O}(0.1~{\rm m}-100~{\rm m}$) and then subsequently decay into final states that include electrons. We consider the effect of several different kinematic cuts for a timing based analysis of this model. We …
We present a systematic approach to solve analytically for the right-handed quark mixings in the minimal left-right symmetric model which generally has both explicit and spontaneous CP violations. The leading-order result has the same hierarchical structure as the left-handed CKM mixing, but with additional CP phases originating from a spontaneous CP-violating phase in the Higgs vev. We explore the phenomenology entailed by the new right-handed mixing matrix, particularly the bounds on the mass of $W_R$ and the CP phase of the Higgs vev.
Following previous work, we identify a symmetry S_nat that generalizes the concept of custodial symmetry, keeping under control deviations from the Standard Model (SM). To realize S_nat linearly, the space of gauge fields has to be extended. Covariant constraints formulated in terms of spurions reduce S_nat back to SU(2)_L x U(1)_Y. This allows for a covariant introduction of explicit S_nat-breaking parameters. We assume that S_nat is at play in a theory of electroweak symmetry-breaking without a light Higgs particle. We describe some consequences of this assumption, using a non-decoupling eff…
We investigate the Higgs inflation and the Higgs portal dark matter with the right-handed neutrino. The dark matter and the right-handed neutrino in the Higgs inflation play important roles in explaining the recent experimental results of the Higgs and top masses, and the cosmic microwave background by BICEP2 at the same time. This inflation model predicts $805~{\rm GeV} \lesssim m_{\rm DM} \lesssim1220~{\rm GeV}$ for the DM mass, $1.05 \times10^{14}~{\rm GeV} \lesssim M_R \lesssim 2.04 \times10^{14}~{\rm GeV}$ for the right-handed neutrino mass, and $8.42 \lesssim ξ\lesssim 12.4$ for the non-…
We compute the one loop corrections to the CP even Higgs mass matrix in the supersymmetric inverse seesaw model to single out the different cases where the radiative corrections from the neutrino sector could become important. It is found that there could be a significant enhancement in the Higgs mass even for Dirac neutrino masses of $\mathcal{O}$(30) GeV if the left-handed sneutrino soft mass is comparable or larger than the right-handed neutrino mass. In the case where right-handed neutrino masses are significantly larger than the supersymmety breaking scale, the corrections can utmost acco…
We discuss the Higgs inflation scenario with singlet scalar dark matter and a right-handed neutrino. The singlet scalar and the right-handed neutrino play crucial roles for realizing a suitable plateau of Higgs potential with the center value of the top mass of Tevatron and LHC measurements. This Higgs inflation scenario predicts about a 1 TeV scalar dark matter and an $\mathcal{O}(10^{14})$ GeV right-handed neutrino by use of 125.6 GeV Higgs mass, 173.34 GeV top mass, and a nonminimal gravity coupling $ξ\simeq10.1$. This inflation model is consistent with the recent result of the tensor-to-sc…
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…
The generation structure in the quark and lepton spectrum is explained as originating from the excitation spectrum S_n of SU(2)_W doublet scalar fields, whose ground state S_1 is the Standard Model Higgs field. There is only one basic family of SU(2)_W doublet left-handed fermions, nu_L, e_L, u_L, d_L, whose bound states with S_n manifest themselves as the generations of left-handed quarks and leptons. Likewise, there is only one basic family of the right-handed fermions, nu_R, e_R, u_R, d_R, which combine with the gauge invariant scalar fields G_n to produce the right-handed quarks and lepton…
We study the collider signatures of the left-right twin Higgs model in the case that the right-handed neutrino mass is less than the mass of the right-handed gauge boson. In this scenario, new leptonic decay chains open up, allowing the particles which cancel the one-loop quadratic divergences of the Higgs, the right-handed gauge bosons and top-partners, to be discovered. Half of these events contain same-sign leptons without missing energy, which have no genuine standard model background and for which the backgrounds are purely instrumental. These signals may be used to complement other colli…
We explore in this paper certain phenomenological consequences - to be tested at the LHC - regarding the scalar sector of a SU(3)xSU(3)xU(1) gauge model with right-handed neutrinos. Our analysis is performed in a particular theoretical approach of treating gauge models with spontaneous symmetry breaking in which a single free parameter 'a' finally remains to be tuned, once all the Standard Model phenomenology is recovered. It is also proved that this particular method is flexible enough as to accommodate the traditional approach in which three VEVs supply masses for gauge bosons and fermions, …
In minimal left-right symmetric theories, the requirement of parity invariance allows only one complex phase in the Higgs potential and one in the Yukawa couplings, leading to a two-phase theory with both spontaneous and explicit CP violations. We present a systematic way to solve the right-handed quark mixing matrix analytically in this model and find that the leading order solution has the same hierarchical structure as the left-handed CKM matrix with one more CP-violating phase coming from the complex Higgs vev. Armed with this explicit right-handed mixing matrix, we explore its implication…
We consider the possibility to explain the recent $R_K$ and $R_{K ^*}$ anomalies in a 2-Higgs Doublet Model, known as Aligned, combined with a low scale seesaw mechanism generating light neutrino masses and mixings. In this class of models, a large Yukawa coupling allows for significant non-universal leptonic contributions, through box diagrams mediated by charged Higgs bosons and right-handed neutrinos, to the $b \to s \ell^+ \ell^-$ transition that can then account for both $R_K$ and $R_{K^*}$ anomalies.
Relic abundance of dark matter is investigated in the framework of universal extra dimension (UED) models with right-handed neutrinos. These models are free from the KK graviton problem in the minimal UED model. The first KK particle of the right-handed neutrino is a dark matter candidate in this framework. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the dark matter relic abundance can increase significantly. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of UED models with right-hande…
We explore the intermediate dark matter mass regime of the inert Higgs doublet model (IHDM) by extending the model with three copies of right handed singlet neutrinos. The in built discrete $Z_2$ symmetry of the model allows these right handed neutrinos to couple to the usual lepton doublets through the inert Higgs doublet allowing the possibility of radiative neutrino mass in the scotogenic fashion. Apart from generating non-zero neutrino mass, such an extension can also revive the intermediate dark matter mass regime, between $W$ boson mass to a few hundred GeV's where pure IHDM can not give…
We investigate the predictions on the mass spectrum and Higgs boson decays in the supersymmetric standard model extended by U(1)_B-L symmetry (BLSSM). The model requires two singlet Higgs fields, which are responsible for the radiative breaking of U(1)_B-L symmetry. It predicts degenerate right-handed neutrino masses (1.7-2.2 TeV) as well as the right-handed sneutrinos of mass <~ 4 TeV. The presence of right-handed neutrinos and sneutrinos trigger the baryon and lepton number violation processes, until they decouple from the Standard model particles. Besides, the model predicts rather heavy co…
When the Higgs field starts oscillation after Higgs inflation, gauge bosons are produced non-perturbatively near the Enhanced Symmetry Point (ESP). Just after the particle production, when the Higgs field is going away from the ESP, these gauge bosons gain mass and decay or annihilate into Standard Model (SM) fermions. Left-handed neutrinos can be generated in that way. If one assumes the see-saw mechanism, the mass matrix of a pair of left and right-handed neutrinos is non-diagonal. Although their mixing in the mass eigenstates is negligible in the true vacuum, it could be significant near th…
Recent observation of high energy neutrino in IceCube experiment suggests existence of superheavy dark matter beyond PeV. We identify the parent particles of neutrino as two degenerated right handed neutrinos, assuming the dark matter is the heaviest right handed neutrino. The $O(V_{cb})\sim O(10^{-2})$ flavor symmetry breaking accounts for the $O(10^{-4})$ mass degeneracy of right handed neutrinos which is a sizable scale to explain the successful resonant leptogenesis at the PeV scale. At the same time, non-thermal production of the heaviest right handed neutrino gives the right amount of da…
We discuss the realization of a vanishing effective Higgs potential at the Planck scale, which is required by the multiple-point criticality principle (MPCP), in the standard model with singlet scalar dark matter and a right-handed neutrino. We find the scalar dark matter and the right-handed neutrino play crucial roles for realization of the MPCP, where a neutrino Yukawa becomes effective above the Majorana mass of the right-handed neutrino. Once the top mass is fixed, the MPCP at the (reduced) Planck scale and the suitable dark matter relic abundance determine the dark matter mass, $m_S$, an…
We discuss phenomenological consequences of some class of supersymmetric seesaw models in which the right-handed (s)neutrino mass is given to be TeV scale. In this scenario, scalar trilinear interaction of Higgs-slepton-(right-handed) sneutrino is enhanced. We show that the 1-loop correction by sneutrino exchange to the lightest Higgs boson mass destructively interferes with top-stop contributions in the minimal SUSY Standard Model. We find that a decay of charged Higgs boson into sneutrino and charged slepton is sizably enhanced and hence it gives rise to a distinctive signal at future collid…
We show that in the framework of the 3-3-1 model with right-handed neutrinos, small neutrino masses and large lepton flavor violating processes such as μ\to 3e and μ\to eγcan be obtained by just introducing an additional Higgs sextet. In the limit of vanishing of the Yukawa interaction among Higgs and lepton triplets (h^ν= 0), the decay μ\to 3e strongly depends on the neutrino mass patterns, but the μ\to eγalmost does not. The neutrino masses are not constrained by such processes in the cases of h^ν\neq 0.
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…
To address five fundamental shortcomings of the Standard Model (SM) of particle physics and cosmology, we propose a SMART U(1)$_X$ model which is a $U(1)_X \times U(1)_{PQ}$ extension of the SM. The $U(1)_X$ gauge symmetry is a generalization of the well-known $U(1)_{B-L}$ symmetry and $U(1)_{PQ}$ is the global Peccie-Quinn (PQ) symmetry. Three right handed neutrinos are added to cancel $U(1)_X$ related anomalies, and they play a crucial role in understanding the observed neutrino oscillations and explaining the observed baryon asymmetry in the universe via leptogenesis. The PQ symmetry helps …
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…
