Portal Dark Matter Research Articles

Addendum to “Invisible Higgs decay width versus dark matter direct detection cross section in Higgs portal dark matter models”

This article is an addendum to Ref.~\cite{Baek:2014jga}. Here, we discuss the invisible Higgs decay width $\Gamma_{h}^{\rm inv}$ in the Higgs portal vector dark matter (VDM) model in the limit $m_V \rightarrow 0^+$. In the effective field theory (EFT) approach where the VDM mass is attributed to the St\"{u}ckelberg mechanism, $( \Gamma_{h}^{\rm inv} )_{\rm EFT}$ is divergent, which is unphysical and puzzling. On the other hand $( \Gamma_{h}^{\rm inv} )_{\rm UV}$ becomes finite in a UV completion, where the VDM mass is generated by the dark Higgs mechanism. Then we can take the limit $m_V \rightarrow 0^+$ by taking either {\it (i)} the dark gauge coupling $g_X \rightarrow 0^+$ with a fixed dark Higgs vacuum expectation value $v_\Phi$, or {\it (ii)} $v_\Phi \to 0^+$ with a fixed $g_X$. Such a difference in the behavior of $\Gamma_{h}^{\rm inv}$ in the massless VDM limit demonstrates another limitation of EFT for the Higgs portal VDM, and the importance of gauge-invariant and renormalizable models for the Higgs portal VDM.

Measurement of high energy dark matter from the Sun at IceCube

It is assumed that heavy dark matter particles (HDMs) with a mass of O(TeV) are captured by the Sun. HDMs can decay to relativistic light dark matter particles (LDMs), which could be measured by km3 neutrino telescopes (like the IceCube detector). The numbers and fluxes of expected LDMs and neutrinos were evaluated at IceCube with the Z′ portal dark matter model. Based on the assumption that no events are observed at IceCube in 6 years, the corresponding upper limits on LDM fluxes were calculated at 90% C. L.. These results indicated that LDMs could be directly detected in the O(1TeV)-O(10TeV) energy range at IceCube with 100 GeV ≲ mZ′ ≲ 350 GeV and τϕ ≲ 5 × 1022ṡ.

Light Dirac neutrino portal dark matter with observable ΔN eff

We propose a Dirac neutrino portal dark matter scenarioby minimally extending the particle content of the Standard Model(SM) with three right-handed neutrinos (ν R ), a Dirac fermiondark matter candidate (ψ) and a complex scalar (ϕ), allof which are singlets under the SM gauge group. An additional ℤ4symmetry has been introduced for the stability of dark mattercandidate ψ and also ensuring the Dirac nature of lightneutrinos at the same time. Both the right handed neutrinos andthe dark matter thermalise with the SM plasma due to a new Yukawainteraction involving ν R , ψ and ϕ while the lattermaintains thermal contact via the Higgs portal interaction.The decoupling of ν R occurs when ϕloses its kinetic equilibrium with the SM plasma and thereafterall three ℤ4 charged particles form an equilibriumamong themselves with a temperature TνR .The dark matter candidate ψ finally freezes out within the darksector and preserves its relic abundance. We have found that in thepresent scenario, some portion of low mass dark matter (M ψ ≲ 10 GeV)is already excluded by the Planck 2018 data for keeping ν R sin the thermal bath below a temperature of 600 MeV and therebyproducing an excess contribution to N eff. The nextgeneration experiments like CMB-S4, SPT-3G etc. will have the required sensitivities to probe the entiremodel parameter space of this minimal scenario,especially the low mass range of ψ where direct detectionexperiments are still not capable enough for detection.

Complementarity between dark matter direct searches and CE\u03bdNS experiments in U(1)\u2032 models

We explore the possibility of having a fermionic dark matter candidate within U(1)′ models for CEνNS experiments in light of the latest COHERENT data and the current and future dark matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under U(1)′ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CEνNS experiments and dark matter direct detection searches to explore dark matter as well as Z′ boson parameter space. Depending on numerous other constraints arising from the beam dump, LHCb, BABAR, and the forthcoming reactor experiment proposed by the SBC collaboration, we explore the allowed region of Z′ portal dark matter.

Searching for lepton portal dark matter with colliders and gravitational waves

We study the lepton portal dark matter (DM) model in which the relic abundance is determined by the portal coupling among the Majorana fermion DM candidate χ, the singlet charged scalar mediator S± and the Standard Model (SM) right-handed lepton. The direct and indirect searches are not sensitive to this model. This article studies the lepton portal coupling as well as the scalar portal coupling (between S± and SM Higgs boson), as the latter is generally allowed in the Lagrangian. The inclusion of scalar portal coupling not only significantly enhances the LHC reach via the gg → h* → S+S− process, but also provides a few novel signal channels, such as the exotic decays and coupling devi- ations of the Higgs boson, offering new opportunities to probe the model. In addition, we also study the Drell-Yan production of S+S− at future lepton colliders, and find out that the scenario where one S± is off-shell can be used to measure the lepton portal coupling directly. In particular, we are interested in the possibility that the scalar potential triggers a first-order phase transition and hence provides the stochastic gravitational wave (GW) signals. In this case, the terrestrial collider experiments and space-based GW detectors serve as complementary approaches to probe the model.

Measurement of TeV dark particles due to decay of heavy dark matter in the earth core at IceCube

Abstract In an alternative dark matter scenario, it is assumed that there exist two species of dark matter: a heavy dark matter particle (HDM) with the mass of O(TeV) which is generated in early universe and a lighter dark matter particle (LDM) which is a relativistic product due to the decay of HDM. HDMs, captured by the earth, decay to high energy LDMs, and these particles can be measured by km 3 neutrino telescopes, like the IceCube detector. In the present paper, a Z ′ portal dark matter model is taken for LDMs to interact with nuclei via a neutral current interaction mediated by a heavy gauge boson Z ′ . With the different lifetimes of decay of HDMs and Z ′ masses, the event rates of expected LDMs and neutrinos were evaluated at IceCube in the energy range between 1 TeV and 100 TeV. According to the IceCube data, the upper limit for LDM fluxes was estimated at 90% C.L. at IceCube. With m Z ′ ≲ 250 G e V and τ ϕ ≲ 1 0 20 s, finally, it is proved that LDMs could be directly measured in the energy range between O(1TeV) and O(10TeV) at IceCube.

A closer look at CP-violating Higgs portal dark matter as a candidate for the GCE

A statistically significant excess of gamma rays has been reported and robustly confirmed in the Galactic Center over the past decade. Large local dark matter densities suggest that this Galactic Center Excess (GCE) may be attributable to new physics, and indeed it has been shown that this signal is well-modelled by annihilations dominantly into boverline{b} with a WIMP-scale cross section. In this paper, we consider Majorana dark matter annihilating through a Higgs portal as a candidate source for this signal, where a large CP-violation in the Higgs coupling may serve to severely suppress scattering rates. In particular, we explore the phenomenology of two UV completions, a singlet-doublet model and a doublet-triplet model, and map out the available parameter space which can give a viable signal while respecting current experimental constraints.

Dark Matter production from relativistic bubble walls

In this paper we present a novel mechanism for producing the observed Dark Matter (DM) relic abundance during the First Order Phase Transition (FOPT) in the early universe. We show that the bubble expansion with ultra-relativistic velocities can lead to the abundance of DM particles with masses much larger than the scale of the transition. We study this non-thermal production mechanism in the context of a generic phase transition and the electroweak phase transition. The application of the mechanism to the Higgs portal DM as well as the signal in the Stochastic Gravitational Background are discussed.

The CP violation and scalar dark matter in a 331 model

The 331 model with right-handed neutrinos is reassessed to investigate the CP violation in the quark sector. After the spontaneous symmetry breaking, the masses and physical fields of the particle content are obtained. The fermions content of the 331 model is enlarged to include exotic quarks with known electric charge and with masses defined at the TeV scale. The existence of these exotic quarks induces extra CP violations via couplings with quarks of the Standard Model mediated by charged gauge boson with mass fixed at the TeV scale. An extra discrete [Formula: see text] symmetry is introduced in the 331 model to get a stable scalar field that can be a candidate to the dark matter content. The new scalar field interacts at the tree level with the [Formula: see text] gauge boson that works as a dark matter portal. The relic density associated with the scalar field is calculated to yield the solution mass that satisfies the observed dark matter. The region allowed on the parameter space of the dark matter mass versus [Formula: see text] mass is obtained to include the bounds of PANDAX2017, XENON1T(2t.y) and LUX experiments.

Light mass window of lepton portal dark matter

We explore a novel possibility that dark matter has a light mass below 1 GeV in a lepton portal dark matter model. There are Yukawa couplings involving dark matter, left-handed leptons and an extra scalar doublet in the model. In the light mass region, dark matter is thermally produced via its annihilation into neutrinos. In order to obtain the correct relic abundance and avoid collider bounds, a neutral scalar is required to be light while charged scalars need to be heavier than the electroweak scale. Such a mass spectrum is realized by adjusting quartic couplings in the scalar potential or introducing an extra singlet scalar. It turns out that the mass region of 10 MeV–10 GeV is almost free from experimental and observational constraints. We also point out that searches for extra neutrino flux from galactic dark matter annihilations with neutrino telescopes are the best way to test our model.

An interpretation of a simple portal dark matter model on Fermi-LAT gamma-ray excess

Dark matter is one of the main components of the universe. Due to its weak interaction with other particles, dark matter cannot be identified as a particle that we know of. We are interested in a simple particle physics scenario where dark matter is identified with the fermion in the dark sector and the standard model sector is connected to dark matter via the portal scalar field. One of the promising signals from these models are gamma-rays from dark matter annihilation processes. In 2016, the Fermi-LAT collaboration detected a gamma-ray excess signal coming from Milky Way’s galactic center which was immediately regarded as a possible candidate for the first detection of dark matter. In this project, we study an interpretation of the signal from Fermi-LAT as a dark matter annihilation from portal dark matter model. First, we calculated gamma-ray fluxes from dark matter annihilations as subsequent decays of portal scalars where the astrophysical factor is calculated from the Navarro-Frenk-White (NFW) dark matter density profile. We found that the simplest model does not fit adequately with chi-squared per degree of freedom, . We proposed that a part of the Fermi-LAT excess might come from another source of gamma-ray. The dark matter model combined with an unknown astrophysical source is then studied. The combined model is able to provide a reasonable fit indicating that scalar mass is 130 GeV, where dark matter mass is in the range of 150 − 350 GeV and 〈σν〉 is around 7 × 10−26 cm3/s.

Lepton dark matter portal in the inert Zee model

The inert Zee model is an extension of the Zee model for neutrino masses. This new model explains the dark matter relic abundance, generates a one-loop neutrino masses and forbids tree-level Higgs-mediated flavor changing neutral currents. Although the dark matter phenomenology of the model is similar to that of the inert doublet model, the presence of new vector-like fermions opens the lepton portal as a new dark matter annihilation channel. We study the impact of this new portal in the low-mass regime and show the parameter space allowed by direct and indirect searches of dark matter. Remarkably, the region for [Formula: see text] GeV is recovered for [Formula: see text]. We also show that future experiments like LZ and DARWIN could probe a large region of the parameter space of the model.

Elastic and inelastic scattering of cosmic rays on sub-GeV dark matter

We revisit the signatures from collisions of cosmic-rays on sub-GeV dark matter (DM) in the Milky Way. In addition to the upscattered DM component that can be probed by existing DM and neutrino experiments widely discussed, we examine the associated signals in $\gamma$-rays and neutrinos that span a wide energy range due to the inelastic scatterings. Assuming a simple vector portal DM model for illustration, we compute both the upscattered DM flux by cosmic-ray protons, and the resulting emission of secondary $\gamma$-rays and high-energy neutrinos from proton excitation, hadronization, and the subsequent meson decay. We derive limits on coupling constants in the vector portal model using data from the $\gamma$-ray and high-energy neutrino telescopes including Fermi, H.E.S.S. and IceCube. These limits are compared to those obtained by considering the upscattered DM signals at the low-energy DM/neutrino detectors XENON1T/MiniBooNE and the IceCube. For this particular model, the limits are set predominantly by non-detection of the upscattered DM events in XENON1T, for most of the DM mass range due to the large scattering cross section at low energies. Nevertheless, our study demonstrates that the $\gamma$-ray and neutrino signals, traditionally considered as indirect probes for DM annihilation and decay, can also be directly used to constrain the DM--nucleon interaction in complementary to the direct search experiments.

Self-interacting dark matter from late decays and the H0 tension

We study a dark matter production mechanism based on decays of a messenger WIMP-like state into a pair of dark matter particles that are self-interacting via exchange of a light mediator. Its distinctive thermal history allows the mediator to be stable and therefore avoid strong limits from the cosmic microwave background and indirect detection. A natural by-product of this mechanism is a possibility of a late time, i.e., after recombination, transition to subdominant dark radiation component through three-body and one-loop decays to states containing the light mediator. We examine to what extent such a process can help to alleviate the $H_0$ tension. Additionally, the mechanism can provide a natural way of constructing dark matter models with ultra-strong self-interactions that may positively affect the supermassive black hole formation rate. We provide a simple realization of the mechanism in a Higgs portal dark matter model and find a significant region of the parameter space that leads to a mild relaxation of the Hubble tension while simultaneously having the potential of addressing small-scale structure problems of $\Lambda$CDM.

Current status and muon g \u2212 2 explanation of lepton portal dark matter

In this paper, we summarize phenomenology in lepton portal dark matter (DM) models, where DM couples to leptons and extra leptons/sleptons. There are several possible setups: a DM field is either a complex/real scalar or a Dirac/Majorana fermion, and chiralities of leptons that couple to the DM are different according to the spin of the DM. We discuss the prediction of each model and compare it with the latest experimental constraints from the DM detections, the LHC, and the flavor experiments. We also propose simple setups to resolve the discrepancy in the anomalous magnetic moment of muon.

Feeble neutrino portal dark matter at neutrino detectors

We explore the neutrino portal dark matter (DM) at its minimum of field content having two dark sector particles coupled to a right-handed neutrino. Assuming the feeble nature of their interactions with the standard model (SM) particles, we analyze the freeze-in production of the observed DM relic density characterized by three different categories depending on the major production mechanisms. The portal provides interesting signatures at the neutrino detectors like KamLAND, Super-Kamiokande and IceCube, from a very late decay of the scalar DM to the fermion DM and the SM neutrino. Such neutrino flux spectrum from the cosmic and galactic origins can produce anomalous signals at future experiments.

LHC signals of triplet scalars as dark matter portal: cut-based approach and improvement with gradient boosting and neural networks

We consider a scenario where an SU(2) triplet scalar acts as the portal for a scalar dark matter particle. We identify regions of the parameter space, where such a triplet coexists with the usual Higgs doublet consistently with all theoretical as well as neutrino, accelerator and dark matter constraints, and the triplet-dominated neutral state has substantial invisible branching fraction. LHC signals are investigated for such regions, in the final state same-sign dilepton + ≥ 2 jets +. While straightforward detectability at the high-luminosity run is predicted for some benchmark points in a cut-based analysis, there are other benchmarks where one has to resort to gradient boosting/neural network techniques in order to achieve appreciable signal significance.

Loop dominated signals from neutrino portal dark matter

We study scenarios where loop processes give the dominant contributions to dark matter decay or annihilation despite the presence of tree level channels. We illustrate this possibility in a specific model where dark matter is part of a hidden sector that communicates with the Standard Model sector via a heavy neutrino portal. We explain the underpinning rationale for how loop processes mediated by the portal neutrinos can parametrically dominate over tree level decay channels, and demonstrate that this qualitatively changes the indirect detection signals in positrons, neutrinos, and gamma rays.

Searching for dark photon dark matter with cosmic ray antideuterons

Low energy antideuteron detection presents a unique channel for indirect detection, targeting dark matter that annihilates into hadrons in a relatively background-free way. Since the idea was first proposed, many WIMP-type models have already been disfavored by direct detection experiments, and current constraints indicate that any thermal relic candidates likely annihilate through some hidden sector process. In this paper, we show that cosmic ray antideuteron detection experiments represent one of the best ways to search for hidden sector thermal relic dark matter, and in particular investigate a vector portal dark matter that annihilates via a massive dark photon. We find that the parameter space with thermal relic annihilation and {m}_{chi }>{m}_{Aprime}underset{sim }{>} 20 GeV is largely unconstrained, and near future antideuteron experiment GAPS will be able to probe models in this space with mχ ≈ mA′ up to masses of O (100 GeV). Specifically the dark matter models favored by the Fermi Galactic center excess is expected to be detected or constrained at the 5(3) −σ level assuming a optimistic (conservative) propagation model.

Dark energy from dynamical projective connections

We further develop the gravitational model, Thomas-Whitehead gravity (TW Gravity), that arises when projective connections become dynamical fields. TW Gravity has its origins in geometric actions from string theory where the TW projective connection appears as a rank two tensor, , on the spacetime manifold. Using a Gauss–Bonnet (GB) action built from the -dimensional TW connection, and applying the tensor decomposition , we arrive at a gravitational model made up of a -dimensional Einstein–Hilbert + GB action sourced by Dab and with cosmological constant . The action is studied and we find that , with J0 the coupling constant for Dab. For equal to the current measured value, J0 is on the order of the measured angular momentum of the observable Universe. We view this as controlling the scale of patches of the Universe that acquire angular momentum, with the net angular momentum of multiple patches vanishing, as required by the cosmological principle. We further find a universal axial scalar coupling to all fermions where the trace, acts as the scalar. This suggests that is also a dark matter portal for non-standard model fermions.