Inert Doublet Research Articles

Generalizing the Scotogenic model

The Scotogenic model is an economical setup that induces Majorana neutrino masses at the 1-loop level and includes a dark matter candidate. We discuss a generalization of the original Scotogenic model with arbitrary numbers of generations of singlet fermion and inert doublet scalar fields. First, the full form of the light neutrino mass matrix is presented, with some comments on its derivation and with special attention to some particular cases. The behavior of the theory at high energies is explored by solving the Renormalization Group Equations.

Multicomponent dark matter in extended U(1)B−L: neutrino mass and high scale validity

Standard Model with right handed neutrinos charged under additional U(1)B−L gauge symmetry offer solutions to both dark matter (DM) problem and neutrino mass generation, although constrained severely from relic density, direct search and Higgs vacuum stability. We therefore investigate a multicomponent DM scenario augmented by an extra inert scalar doublet, that is neutral under U(1)B−L, which aids to enlarge parameter space allowed by DM constraints and Higgs vacuum stability. The lightest right-handed neutrino and the CP-even inert scalar are taken as the dark matter candidates and constitute a two component dark matter framework as they are rendered stable by an unbroken ℤ2 × ℤ2′ symmetry. DM-DM conversion processes turn out crucial to render requisite relic abundance in mass regions of the RH neutrino that do not appear in the stand-alone U(1)B−L scenario. In addition, the one-loop renormalisation group (RG) equations in this model demonstrate that the electroweak (EW) vacuum can be stabilised till ∼ 109 GeV in a parameter region compatible with the observed relic, the direct detection bound and other relevant constraints. We finally comment on the possibility of including the freeze-in mechanism in the same set-up.

Two component dark matter with inert Higgs doublet: neutrino mass, high scale validity and collider searches

The idea of this work is to investigate the constraints on the dark matter (DM) allowed parameter space from high scale validity (absolute stability of Higgs vacuum and perturbativity) in presence of multi particle dark sector and heavy right handed neutrinos to address correct neutrino mass. We illustrate a simple two component DM model, consisting of one inert SU(2)L scalar doublet and a scalar singlet, both stabilised by additional {mathcal{Z}}_2times {mathcal{Z}}_2^{prime } symmetry, which also aid to vacuum stability. We demonstrate DM-DM interaction helps achieving a large allowed parameter space for both the DM components by evading direct search bound. High scale validity puts further constraints on the model, for example, on the mass splitting between the charged and neutral component of inert doublet, which has important implication to its leptonic signature(s) at the Large Hadron Collider (LHC).

Constraints on the parameter space in an inert doublet model with two active doublets

We study a three Higgs doublet model where one doublet is inert and the other two doublets are active. Flavor changing neutral currents are avoided at tree-level by imposing a softly broken {Z}_2^{prime } symmetry and we consider type I and type II Yukawa structures. The lightest inert scalar is a viable Dark Matter (DM) candidate. A numerical scan of the free parameters is performed taking into account theoretical constraints such as positivity of the scalar potential and unitarity of 2 → 2 scattering amplitudes. The model is further constrained by experimental results such as B physics lower limits on charged Higgs masses, Electroweak Precision Observables, LEP II, LHC Higgs measurements, Planck measurement of the DM relic abundance and WIMP direct searches by the LUX and XENON1T experiments. The model predictions for mono-jet, mono Z and mono Higgs final states are studied and tested against current LHC data and we find the model to be allowed. We also discuss the effects of abandoning the “dark democracy” assumption common in studies of inert models. Projected sensitivities of direct detection experiments will leave only a tiny window in the DM mass versus coupling plane that is compliant with relic density bounds.

Leading two-loop corrections to the Higgs boson self-couplings in models with extended scalar sectors

We compute the dominant two-loop corrections to the Higgs trilinear coupling lambda _{hhh} and to the Higgs quartic coupling lambda _{hhhh} in models with extended Higgs sectors, using the effective-potential approximation. We provide in this paper all necessary details about our calculations, and present general overline{{mathrm{MS}}} expressions for derivatives of the integrals appearing in the effective potential at two loops. We also consider three particular Beyond-the-Standard-Model (BSM) scenarios – namely a typical scenario of an Inert Doublet Model (IDM), and scenarios of a Two-Higgs-Doublet Model (2HDM) and of a Higgs Singlet Model (HSM) without scalar mixing – and we include all the necessary finite counterterms to obtain (in addition to overline{{mathrm{MS}}} results) on-shell scheme expressions for the corrections to the Higgs self-couplings. With these analytic results, we investigate the possible magnitude of two-loop BSM contributions to the Higgs self-couplings and the fate of the non-decoupling effects that are known to appear at one loop. We find that, at least as long as pertubative unitarity conditions are fulfilled, the size of two-loop corrections remains well below that of one-loop corrections. Typically, two-loop contributions to lambda _{hhh} amount to approximately 20% of those at one loop, implying that the non-decoupling effects observed at one loop are not significantly modified, but also meaning that higher-order corrections need to be taken into account for the future perspective of precise measurements of the Higgs trilinear coupling.

Complex scalar dark matter in the gauged two-Higgs-doublet model

The complex scalar dark matter (DM) candidate in the gauged two Higgs doublet model (G2HDM), stabilized by a peculiar hidden parity ($h$-parity), is studied in detail. We explore the parameter space for the DM candidate by taking into account the most recent DM constraints from various experiments, in particular, the PLANCK relic density measurement and the current DM direct detection limit from XENON1T. We separate our analysis in three possible compositions for the mixing of the complex scalar. We first constrain our parameter space with the vacuum stability and perturbative unitarity conditions for the scalar potential, LHC Higgs measurements, plus Drell-Yan and electroweak precision test constraints on the gauge sector. We find that DM dominated by composition of the inert doublet scalar is completely excluded by further combining the previous constraints with both the latest results from PLANCK and XENON1T. We also demonstrate that the remaining parameter space with two other DM compositions can be further tested by indirect detection like the future CTA gamma-ray telescope.

Dirac neutrino mass generation from a Majorana messenger

The radiative type-I seesaw has been already implemented to explain the lightness of Majorana neutrinos with both Majorana and Dirac heavy fermions, and the lightness of Dirac neutrinos with Dirac heavy fermions. In this work we present a minimal implementation of the radiative type-I seesaw with light Dirac neutrinos and heavy Majorana fermions. An inert doublet and a complex singlet scalar complete the dark sector which is protected by an Abelian fermiophobic gauge symmetry that also forbids tree level mass contributions for the full set of light neutrinos. A fermion vector-like extension of the model is also proposed where the light right-handed neutrinos can thermalize in the primordial plasma and the extra gauge boson can be directly produced at colliders. In particular, the current upper bound on $\Delta N_{\text{eff}}$ reported by PLANCK points to large ratios $M_{Z'}/g'\gtrsim 40\ \text{TeV}$ which can be competitive with collider constraint for $g'$ sufficiently large in the ballpark of the Standard Model values, while future cosmic microwave background experiments may probe all the no minimal models presented here.

Exploring Dark Matter, Neutrino mass and flavour anomalies in L μ – L τ model

We investigate Majorana dark matter in a new variant of U(1) Lμ – Lτ gauge extension of Standard Model, containing three additional neutral fermions Ne, Nμ, Nτ , along with a (, 1, 1/3) scalar Leptoquark (SLQ) and an inert doublet, to study the phenomenology of dark matter, neutrino mass generation and flavour anomalies on a single platform. The lightest mass eigenstate of the Nμ, Nτ neutral fermions plays the role of dark matter. We compute the WIMP-nucleon cross section in leptoquark portal and the relic density mediated by inert doublet components, leptoquark and the new Z′ boson. We constrain the parameter space consistent with Planck limit on relic density, PIC0-60 and LUX bounds on spin-dependent direct detection cross section. We also discuss about the neutrino mass generation at one-loop level and the viable parameter region to explain current neutrino oscillation data. The Z′ gauge boson of extended U(1) symmetry and the SLQ play an important role in settling the known issues of flavor sector.

Gauged U(1)_{L_mu -L_tau } scotogenic model in light of R_{K^{(*)}} anomaly and AMS-02 positron excess

We study the gauged U(1)_{L_mu -L_tau } scotogenic model with emphasis on latest measurement of LHCb R_{K^{(*)}} anomaly and AMS-02 positron excess. In this model, neutrino masses are induced at one-loop level with Z_2-odd particles, i.e., right-handed neutrinos N_ell (ell =e,mu ,tau ) and inert scalar doublet eta inside the loop. Meanwhile, the gauged U(1)_{L_mu -L_tau } symmetry is broken spontaneously by the scalar singlet S, resulting to the massive gauge boson Z'. Provided certain couplings to quarks induced by heavy vector-like quarks, the gauge boson Z' would contribute to the transition brightarrow s mu ^+mu ^-, hence explain the R_{K^{(*)}} anomaly. As for the Majorana fermion DM N, the gauge boson Z' and the singlet Higgs H_0 will generate various annihilation channels, among which the NNrightarrow Z'Z' and NNrightarrow Z'H_0(rightarrow Z'Z') channel could be used to interpret the AMS-02 positron excess. We give a comprehensive analysis on model parameter space with consider various current constraints. The combined analysis shows that the R_{K^{(*)}} anomaly and AMS-02 positron excess can be explained simultaneously.

Relic density of dark matter in the inert doublet model beyond leading order: The heavy mass case

A full renormalisation of the Inert Doublet Model (IDM) is presented and exploited for a precise calculation of the relic density of Dark Matter (DM) at one-loop. In this first paper, we study the case of a DM candidate with $m_{\rm DM} \sim 500$ GeV. In this regime, the co-annihilation channels are important. We therefore compute, for a wide range of relative velocities, the full next-to-leading order electroweak corrections to 7 annihilation/co-annihilation processes that contribute $\sim$ 70\% to the relic density of DM. These corrected cross-sections are interfaced with {\tt micrOMEGAs} to obtain the one-loop correction to the freeze-out relic density. Due to the accurate measurement of this observable, the one-loop corrections are relevant. We discuss the one-loop renormalisation scheme dependence and point out the influence, at one-loop, of a parameter that solely describes the scattering in the dark sector. A tree-level computation of the relic density is not sensitive to this parameter.

Dark matter from the inert Higgs doublet model

Dark matter is a clear evidence of new physics beyond the Standard Model. In this work, we consider the inert doublet model where dark matter is a member of a new Higgs doublet. In this scenario, dark matter properties can be calculated. We then test model predictions against experimental results such as the LHC Higgs data, the electroweak precision measurements and dedicated dark matter searches. In addition, we subject the model to theoretical constraints: perturbativity, vacuum stability and unitarity. Finally, we identify the viable parameter space of the model.

Constraining the Inert Doublet Model using Vector Boson Fusion

In this work, we use a recast of the Run II search for invisible Higgs decays within Vector Boson Fusion to constrain the parameter space of the Inert Doublet model, a two Higgs doublet model with a dark matter candidate. When including all known theoretical as well as collider constraints, we find that the above can rule out a relatively large part in the m_H,,lambda _{345} parameter space, for dark scalar masses m_H,le ,100,{mathrm{GeV}}. Including the latest dark matter constraints, a smaller part of parameter space remains which is solely excluded from the above analysis. We also discuss the sensitivity of monojet searches and multilepton final states from Run II.

A simple model to explain observed muon sector anomalies and small neutrino masses

Since its inception, no decisive departure from the predictions of the standard model (SM) has been reported. However, recently various experiments have observed a few hints of possible departure from SM predictions in lepton flavor universality observables such as , , muon (g–2), , etc. Many of these are observable where deviation from the SM in the range of (2–4)σ is observed related to the muon (μ) lepton. So these deviations may hint at a possible new physics (NP) in the muon sector. In this work we extend the SM by introducing two SM singlet heavy charged leptons (Fe, Fμ), whose left-handed components are charged under a new U(1)F gauge symmetry, one color triplet lepto-quark (ϕQ) doublet under SU(2)L, one inert Higgs doublet (ϕl), and three very heavy Majorana neutrinos (NiR), all of which are odd under a Z2 discrete symmetry. One more scalar (ϕ) charged only under the U(1)F, whose VEV gives masses to the U(1)F gauge boson as well as the heavy leptons. With these new particles, we show that the observed anomalies in the muon sector as well as small neutrino masses can be explained taking into account all the other experimental and theoretical constraints to date.

Full next-to-leading-order calculations of Higgs boson decay rates in models with non-minimal scalar sectors

We present a complete set of decay rates of the Higgs boson with the mass of 125 GeV at the full next-to-leading order in a variety of extended Higgs models; i.e., a model with an additional real singlet scalar field, four types of two Higgs doublet models and the inert doublet model. All the one-loop contributions due to QCD and electroweak interactions as well as scalar interactions are taken into account, and the calculations are systematically performed. Branching ratios for all the decay modes are evaluated in these models, and patterns of deviations in each decay mode from the standard model predictions are comprehensively analyzed. We show how these models with extended Higgs sectors can be distinguished by using our calculation of the branching ratios and future precision measurements of the Higgs boson decays.

Gravitational wave signatures from an extended inert doublet dark matter model

We consider a particle dark matter model by extending the scalar sector of the Standard Model by an additional SU(2) scalar doublet which is made “inert” (and stable) by imposing a discrete Z2 symmetry under which the additional scalar doublet is odd (and the SM is even) and it does not develop any vacuum expectation value (VEV) . The lightest inert particle (LIP) of this inert doublet model (IDM) can be a viable candidate for Dark Matter. The IDM model is further extended by an additional singlet scalar which is also even under Z2 and develop a VEV on spontaneous symmetry breaking. This additional scalar singlet mixes with SM Higgs and on diagonalisation of the mass matrix two CP even scalar eigenstates are obtained one of which is attributed to the physical Higgs (with mass 125.09 GeV) . The LIP is the dark matter candidate in the extended model. For such a particle dark matter model we explore the first-order electroweak phase transition and consequent production of Gravitational Waves (GW) at that epoch of the early Universe and calculate the intensities and frequencies for such waves. We then investigate the detection possibilities of such GWs at the future spaceborne primordial GW detectors such as eLISA, BBO, ALIA, DECIGO, U-DECIGO and ground-based detector aLIGO.

Probing the inert doublet model using jet substructure with a multivariate analysis

We explore the challenging but phenomenologically interesting hierarchical mass spectrum of the Inert Doublet Model where relatively light dark matter along with much heavier scalar states can fully satisfy the constraints on the relic abundance and also fulfill other theoretical as well as collider and astrophysical bounds. To probe this region of parameter space at the LHC, we propose a signal process that combines up to two large radius boosted jets along with substantial missing transverse momentum. Aided by our intuitive signal selection, we capture a hybrid process where the di-fatjet signal is significantly enhanced by the mono-fatjet contribution with minimal effects on the SM di-fatjet background. Substantiated by the sizable mass difference between the scalars, these boosted jets, originally produced from the hadronic decay of massive vector bosons, still carry the inherent footprint of their root. These features implanted inside the jet substructure can provide additional handles to deal with a large background involving QCD jets. We adopt a multivariate analysis using boosted decision tree to provide a robust mechanism to explore the hierarchical scenario, which would bring almost the entire available parameter space well within reach of the 14 TeV LHC runs with high luminosity.

Minimal two-component scalar doublet dark matter with radiative neutrino mass

We propose a minimal extension of the Standard Model to accommodate two-component dark matter (DM) and light neutrino mass. The symmetry of the Standard Model is enhanced by an unbroken ${\mathbb{Z}}_{2}\ifmmode\times\else\texttimes\fi{}{\mathbb{Z}}_{2}^{\ensuremath{'}}$ such that being odd under each ${\mathbb{Z}}_{2}$, there exists one right-handed neutrino and one inert scalar doublet. Therefore, each of the ${\mathbb{Z}}_{2}$ sectors contribute to (i) light neutrino masses radiatively similar to the scotogenic models while (ii) the two neutral $CP$ even scalars present in two additional inert doublets play the role of dark matters. Focusing on the intermediate range of inert scalar doublet DM scenario: ${M}_{W}\ensuremath{\le}{M}_{\mathrm{DM}}\ensuremath{\lesssim}\phantom{\rule{0ex}{0ex}}500\text{ }\text{ }\mathrm{GeV}$, where one scalar doublet DM cannot satisfy correct relic, we show that this entire range becomes allowed within this two-component scalar doublet DM, thanks to the interconversion between the two DM candidates in the presence of neutrino Yukawa couplings with dark sector.

Planck scale origin of nonzero θ13 and super-WIMP dark matter

We study a discrete flavour symmetric scenario for neutrino mass and dark matter under the circumstances where such global discrete symmetries can be explicitly broken at Planck scale, possibly by gravitational effects. Such explicit breaking of discrete symmetries mimic as Planck suppressed operators in the model which can have non-trivial consequences for neutrino and dark matter sectors. In particular, we study a flavour symmetric model which, at renormalisable level, gives rise to tri-bimaximal type neutrino mixing with vanishing reactor mixing angle $\theta_{13}=0$, a stable inert scalar doublet behaving like a weakly interacting massive particle (WIMP) and a stable singlet inert fermion which does not interact with any other particles. The introduction of Planck suppressed operators which explicitly break the discrete symmetries, can give rise to the generation of non-zero $\theta_{13}$ in agreement with neutrino data and also open up decay channels of inert scalar doublet into singlet neutral inert fermion leading to the realisation of the super-WIMP dark matter scenario. We show that the correct neutrino phenomenology can be obtained in this model while discussing three distinct realisation of the super-WIMP dark matter scenario.

Enhanced Z boson decays as a new probe of first-order electroweak phase transition at future lepton colliders

We study phenomenological consequences of the strong first-order electroweak phase transition in an extension of the standard model with an inert doublet and vector-like leptons motivated by the muon $g-2$ anomaly and dark matter. We find that a condition for the strong first-order electroweak phase transition inevitably induces a large logarithmic enhancement in $Z$ boson decays, which relegates the explanation of the anomalous muon $g-2$ at below 2$\sigma$ level. Our analysis shows that future lepton collider experiments, especially the Giga-$Z$ at the International Linear Collider and Tera-$Z$ at the Circular Electron Positron Collider as well as Future Circular Collider have great capability to explore the nature of the electroweak phase transition, which is complementary to conventional approaches via measurements of the triple Higgs boson coupling and gravitational waves.

Probing multicomponent extension of inert doublet model with a vector dark matter

Although theoretically well-motivated as a minimal consistent dark matter (DM) model, the inert doublet model (IDM) fell short in explaining the existence of DM in the intermediate mass region (100–500 GeV). We try to address this problem by introducing an additional vector dark matter. We show that the relic density of inert dark matter candidate can be enhanced significantly with new interactions in the intermediate mass region 100–500 GeV in the multicomponent dark matter model when compared with the usual single component inert doublet model. We also show that we can get a reasonable excess in the distribution if we do not apply a very hard cut on it as is customary in any dark matter search at the LHC.