Dark Higgs Boson Research Articles

Search for Higgs portal DM at the ILC

Higgs portal dark matter (DM) models are simple interesting and viable DM models. There are three types of the models depending on the DM spin: scalar, fermion and vector DM models. In this paper, we consider renormalizable, unitary and gauge invariant Higgs portal DM models, and study how large parameter regions can be surveyed at the International Linear Collider (ILC) experiment at $\sqrt{s}=500$ GeV. For the Higgs portal singlet fermion and vector DM cases, the force mediator involves two scalar propagators, the SM-like Higgs boson and the dark Higgs boson. We show that their interference generates interesting and important patterns in the mono-$Z$ plus missing $E_T$ signatures at the ILC, and the results are completely different from those obtained from the Higgs portal DM models within the effective field theories. In addition, we show that it would be possible to distinguish the spin of DM in the Higgs portal scenarios, if the shape of the recoil-mass distribution is observed. We emphasize that the interplay between these collider observations and those in the direct detection experiments has to be performed in the model with renomalizability and unitarity to combine the model analyses in different scales.

Dark sector shining through 750 GeV dark Higgs boson at the LHC

We consider a dark sector with $SU(3)_C \times U(1)_Y \times U(1)_X$ and three families of dark fermions that are chiral under dark $U(1)_X$ gauge symmetry, whereas scalar dark matter $X$ is the SM singlet. $U(1)_X$ dark symmetry is spontaneously broken by nonzero VEV of dark Higgs field $\langle \Phi \rangle$, generating the masses of dark fermions and dark photon $Z^\prime$. The resulting dark Higgs boson $\phi$ can be produced at the LHC by dark quark loop (involving 3 generation) and will decay into a pair of photon through charged dark fermion loop. Its decay width can be easily $\sim 45$ GeV due to its possible decays into a pair of dark photon, which is not strongly constrained by the current LHC searches $pp \rightarrow \phi \rightarrow Z^\prime Z^\prime$ followed by $Z^\prime$ decays into the SM fermion pairs. The scalar DM can achieve thermal relic density without conflict with direct detection bound or the invisible $\phi$ decay into a pair of DM.

Dark Higgs channel for Fermi GeV γ-ray excess

Dark Higgs is very generic in dark matter models where DM is stabilized by some spontaneously broken dark gauge symmetries. Motivated by tentative GeV scale γ-ray excess from the galactic center (GC), we investigate a scenario where a pair of dark matter X annihilates into a pair of dark Higgs H2, which subsequently decays into standard model particles through its mixing with SM Higgs boson. Besides the two-body decay of H2, we also include multibody decay channels of the dark Higgs. We find that the best-fit point is around MX ≃ 95.0 GeV, MH2 ≃ 86.7 GeV, ⟨σ v⟩ ≃ 4.0 × 10−26cm3/s and gives a p-value ≃ 0.40. Implication of this result is described in the context of dark matter models with dark gauge symmetries. Since such a dark Higgs boson is very difficult to produce at colliders, indirect DM detections of cosmic γ-rays could be an important probe of dark sectors, complementary to collider searches.

Introduction

Ontology, the study of being, the assessment of the nature of reality, is unavoidable. Every time we utilise, or react to, something, we consider that something according to its nature, whether it be a car, bull, mouse, snake, pencil, chair, mirror or river. Focussing on science, the question is not whether ontological reasoning occurs (of course it does) but whether it figures in a manner that is largely implicit and unacknowledged or explicit and systematic. In the non-social sciences it is frequently the latter. Einstein and Bohr continually debated the nature of the quantum. Today it is the nature of dark matter, black holes and Higgs boson fields that captivate. The electronic accelerator at CERN was constructed with the goal of addressing a series of pressing ontological puzzles and questions. The social realm has its specific ontological concerns. Matters are by no means settled as to the nature of money, firms, technology, industries, markets, institutions, value, gender, development, social power, social relations, norms, rights, obligations, or even on the general nature of society or economy let alone versions referred to as capitalism, socialism, market economies, surplus-based economies and such like. What even is the nature of social being and social causation?

Local Z2 scalar dark matter model confronting galactic GeV-scale γ-ray

We present a scalar dark matter (DM) model where DM (XI) is stabilized by a local Z2 symmetry originating from a spontaneously broken local dark U(1)X. Compared with the usual scalar DM with a global Z2 symmetry, the local Z2 model possesses three new extra fields, dark photon Z′, dark Higgs ϕ and the excited partner of scalar DM (XR), with the kinetic mixing and Higgs portal interactions dictated by local dark gauge invariance. The resulting model can accommodate thermal relic density of scalar DM without conflict with the invisible Higgs branching ratio and the bounds from DM direct detections, thanks to the newly opened channels, XIXI→Z′Z′,ϕϕ. In particular, due to the new particles, the GeV scale γ-ray excess from the Galactic Center (GC) can be originated from the decay of dark Higgs boson which is produced in DM annihilations.

Dark matter, dark radiation and Higgs phenomenology in the hidden sector DM models

I present a class of hidden sector dark matter (DM) models with local dark gauge symmetries, where DM is stable due to unbroken local dark gauge symmetry, or due topology, or it is long-lived because of some accidental symmetries, and the particle contents and their dynamics are completely fixed by local gauge symmetries. In these models, one have two types of natural force mediators, dark gauge bosons and dark Higgs boson, which would affect DM and Higgs phenomenology in important ways. I discuss various phenomenological issues including the ∼ GeV scale γ-ray excess from the galactic center (GC), (in)direct detection signatures, dark radiation, Higgs phenomenology and Higgs inflation assisted by dark Higgs.

Search for the dark photon and the dark Higgs boson at belle.

The dark photon A^{'} and the dark Higgs boson h^{'} are hypothetical constituents featured in a number of recently proposed dark sector models. Assuming prompt decays of both dark particles, we search for their production in the so-called Higgstrahlung channel e^{+}e^{-}→A^{'}h^{'}, with h^{'}→A^{'}A^{'}. We investigate ten exclusive final states with A^{'}→e^{+}e^{-}, μ^{+}μ^{-}, or π^{+}π^{-} in the mass ranges 0.1 GeV/c^{2} <m_{A^{'}}<3.5 GeV/c^{2} and 0.2 GeV/c^{2} <m_{h^{'}}<10.5 GeV/c^{2}. We also investigate three inclusive final states 2(e^{+}e^{-})X, 2(μ^{+}μ^{-})X, and (e^{+}e^{-})(μ^{+}μ^{-})X, where X denotes a dark photon candidate detected via missing mass, in the mass ranges 1.1 GeV/c^{2} <m_{A^{'}}<3.5 GeV/c^{2} and 2.2 GeV/c^{2} <m_{h^{'}}<10.5 GeV/c^{2}. Using the entire 977 fb^{-1} data set collected by Belle, we observe no significant signal. We obtain individual and combined 90% credibility level upper limits on the branching fraction times the Born cross section, B×σ_{Born}, on the Born cross section σ_{Born}, and on the dark photon coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α_{D}×ε^{2}. These limits improve upon and cover wider mass ranges than previous experiments. The limits from the final states 3(π^{+}π^{-}) and 2(e^{+}e^{-})X are the first placed by any experiment. For α_{D} equal to 1/137, m_{h^{'}}< 8 GeV/c^{2}, and m_{A^{'}}<1 GeV/c^{2}, we exclude values of the mixing parameter ε above ∼8×10^{-4}.

νR Dark matter-philic Higgs for 3.5 keV X-ray signal

We suggest a new model of 7 keV right-handed neutrino dark matter inspired by a recent observation of 3.5 keV X-ray line signal in the XMM-Newton observatory. It is difficult to derive the tiny masses with a suitable left–right mixing of the neutrino in a framework of ordinary simple type-I seesaw mechanism. We introduce a new Higgs boson, a dark matter-philic Higgs boson, in which the smallness of its vacuum expectation value can be achieved. We investigate suitable parameter regions where the observed dark matter properties are satisfied. We find that the vacuum expectation value of dark matter-philic Higgs boson should be about 0.17 GeV.

Illuminating dark photons with high-energy colliders

High-energy colliders offer a unique sensitivity to dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model (SM) hypercharge. Dark photons can be detected in the exotic decay of the 125 GeV Higgs boson, h -> Z Z_D -> 4l, and in Drell-Yan events, pp -> Z_D -> ll. If the dark U(1) is broken by a hidden-sector Higgs mechanism, then mixing between the dark and SM Higgs bosons also allows the exotic decay h -> Z_D Z_D -> 4l. We show that the 14 TeV LHC and a 100 TeV proton-proton collider provide powerful probes of both exotic Higgs decay channels. In the case of kinetic mixing alone, direct Drell-Yan production offers the best sensitivity to Z_D, and can probe epsilon >~ 9 x 10^(-4) (4 x 10^(-4)) at the HL-LHC (100 TeV pp collider). The exotic Higgs decay h -> Z Z_D offers slightly weaker sensitivity, but both measurements are necessary to distinguish the kinetically mixed dark photon from other scenarios. If Higgs mixing is also present, then the decay h -> Z_D Z_D can allow sensitivity to the Z_D for epsilon >~ 10^(-9) - 10^(-6) (10^(-10) - 10^(-7)) for the mass range 2 m_mu < m_(Z_D) < m_h/2 by searching for displaced dark photon decays. We also compare the Z_D sensitivity at pp colliders to the indirect, but model-independent, sensitivity of global fits to electroweak precision observables. We perform a global electroweak fit of the dark photon model, substantially updating previous work in the literature. Electroweak precision measurements at LEP, Tevatron, and the LHC exclude epsilon as low as 3 x 10^(-2). Sensitivity can be improved by up to a factor of ~2 with HL-LHC data, and an additional factor of ~4 with ILC/GigaZ data.

Higgs portal vector dark matter for GeV scale γ-ray excess from galactic center

We show that the GeV scale γ-ray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons (VV→ ϕ ϕ), followed by the subsequent decay of ϕ into bb̄ or τ τ̄ . All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavor-dependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T.

Search for Light and Dark Higgs at BaBar

In many new physics extensions of the Standard Model, light pseudoscalar Higgs or dark matter candidates naturally appear. Searches for light and dark Higgs bosons performed with the large e+e− datasets collected by the BaBar experiment at center-of-mass energies around the ϒ resonances are presented.

Self-interacting scalar dark matter with local Z3 symmetry

We construct a self-interacting scalar dark matter (DM) model with local discrete Z3 symmetry that stabilizes a weak scale scalar dark matter X. The model assumes a hidden sector with a local U(1)X dark gauge symmetry, which is broken spontaneously into Z3 subgroup by nonzero VEV of dark Higgs field ϕX (⟨ϕX⟩≠0). Compared with global Z3 DM models, the local Z3 model has two new extra fields: a dark gauge field Z′ and a dark Higgs field ϕ (a remnant of the U(1)X breaking). After imposing various constraints including the upper bounds on the spin-independent direct detection cross section and thermal relic density, we find that the scalar DM with mass less than 125 GeV is allowed in the local Z3 model, in contrary to the global Z3 model. This is due to new channels in the DM pair annihilations open into Z′ and ϕ in the local Z3 model. Most parts of the newly open DM mass region can be probed by XENON1T and other similar future experiments. Also if ϕ is light enough (a few MeV ≲mϕ≲ O(100) MeV), it can generate a right size of DM self-interaction and explain the astrophysical small scale structure anomalies. This would lead to exotic decays of Higgs boson into a pair of dark Higgs bosons, which could be tested at LHC and ILC.

Multilepton Higgs decays through the dark portal

The U(1)_D gauge sector containing one dark Higgs boson h_D and one dark photon \gamma_D may be explored through the decays of the 126 GeV particle discovered at the Large Hadron Collider (LHC), assumed here as the heavier mass eigenstate h_1 in the mixing of the standard model h with h_D. The various decays of h_1 to \gamma_D \gamma_D, h_2 h_2, h_2 \gamma_D \gamma_D and h_2 h_2 h_2 would yield multilepton final states through the mixing of \gamma_D with the photon and the decay h_2 \to \gamma_D \gamma_D, where h_2 is the lighter dark Higgs. Future searches for signals of multilepton jets at the LHC may reveal the existence of this possible dark sector governed simply by the original Abelian Higgs model.

Extended Standard Model in multi-spinor field formalism: Visible and dark sectors

To generalize the Standard Model so as to include dark matter, we formulate a theory of multi-spinor fields on the basis of an algebra that consists of triple-tensor products of elements of the Dirac algebra. Chiral combinations of multi-spinor fields form reducible representations of the Lorentz group possessing component fields with spin 1/2, which we interpret as expressing three ordinary families and an additional fourth family of quarks and leptons. Apart from the gauge and Higgs fields of the Standard Model interacting with the fermions of the three ordinary families, we assume the existence of additional gauge and Higgs fields interacting exclusively with the fermions of the fourth family. While the fields of the Standard Model organize the “visible sector” of our universe, the fields related with the fourth family are presumed to generate a “dark sector” that can contain dark matter. The two sectors possess a channel of communication through the bi-quadratic interaction between visible and dark Higgs fields. After experiencing a common inflationary phase, the two sectors follow a reheating period and weak-coupling paths of thermal histories. We propose scenarios for dark matter that have a tendency to take relatively broad interstellar distributions and examine methods for the detection of the main candidate particles of dark matter. The exchange of superposed fields of the visible and dark Higgs bosons induces weak reaction processes between the fields of the visible and dark sectors, which enables us to have a glimpse of the dark sector.

Dark matter and Higgs bosons in the MSSM

We investigate dark matter (DM) in the context of the minimal supersymmetric extension of the standard model (MSSM). We scan through the MSSM parameter space and search for solutions that (a) are consistent with the Higgs discovery and other collider searches; (b) satisfy the flavor constraints from $B$ physics; (c) give a DM candidate with the correct thermal relic density; and (d) are allowed by the DM direct detection experiments. For the surviving models with our parameter scan, we find the following features: (1) The DM candidate is largely a Bino-like neutralino with non-zero but less than $20\%$ Wino and Higgsino fractions; (2) The relic density requirement clearly pins down the solutions from the $Z$ and Higgs resonances ($Z,h,H,A$ funnels) and co-annihilations; (3) Future direct search experiments will likely fully cover the $Z,h$ funnel regions, and $H,A$ funnel regions as well except for the "blind spots"; (4) Future indirect search experiments will be more sensitive to the CP-odd Higgs exchange due to its $s$-wave nature; (5) The branching fraction for the SM-like Higgs decay to DM can be as high as $10\%$, while those from heavier Higgs decays to neutralinos and charginos can be as high as $20\%$. We show that collider searches provide valuable information complementary to what may be obtained from direct detections and astroparticle observations. In particular, the $Z$- and $h$-funnels with a predicted low LSP mass should be accessible at future colliders. Overall, the Higgs bosons may play an essential role as the portal to the dark sector.

Dark matter and Higgs boson in a model with discrete gauge symmetry

In view of ongoing measurements of the Higgs-like boson at the LHC and direct searches for dark matter, we explore the possibility of accommodating the potential results in a simple new-physics model with discrete gauge symmetry as well as light neutrino masses. Specifically, we study collider and relic-density constraints on the new gauge coupling, predict the cross section of the dark matter scattering off nucleons, and compare it with current direct search data. We also discuss some of the implications if the dark matter is light. The new gauge sector of the model allows it to be compatible with the latest LHC information on the Higgs-like particle and simultaneously satisfy the requirements in its dark matter sector.

Search for Low-Mass Dark-Sector Higgs Bosons

Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb(-1) of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the standard model-dark-sector mixing angle and the dark-sector coupling constant.

Higgs searches and singlet scalar dark matter: Combined constraints from XENON 100 and the LHC

XENON100 and the LHC are two of the most promising machines to test the physics beyond the Standard Model. In the meantime, indirect hints push us to believe that the dark matter and Higgs boson could be the two next fundamental particles to be discovered. Whereas ATLAS and CMS have just released their new limits on the Higgs searches, XENON100 obtained very recently strong constraints on DM-proton elastic scattering. In this work, we show that when we combined WMAP and the most recent results of XENON100, the invisible width of the Higgs to scalar dark matter is negligible($\lesssim 10%$), except in a small region with very light dark matter ($\lesssim 10$ GeV) not yet excluded by XENON100 or around 60 GeV where the ratio can reach 50% to 60%. The new results released by the Higgs searches of ATLAS and CMS set very strong limits on the elastic scattering cross section, even restricting it to the region $8 \times 10^{-46} \mrm{cm^2} \lesssim \sigma_{S-p}^{SI}\lesssim 2 \times 10^{-45} \mrm{cm^{2}}$ in the hypothesis $135 \mrm{GeV} \lesssim M_H \lesssim 155 \mrm{GeV}$.

V-PARTICLE AGAIN?

This talk is mainly based on our previous work.1 We will investigate the possibility of detecting light long-lived particle (LLP) produced by high energy cosmic ray colliding with atmosphere. The LLP may penetrate the atmosphere and decay into a pair of muons near/in the neutrino telescope. Such muons can be treated as the detectable signal for neutrino telescope. The particle with such behavior is very similar with that of the first observed strange particle in cosmic ray events, which was coined historically as "V-particle" in some literature. This study is motivated by recent cosmic electron/positron observations which suggest the existence of O(TeV) dark matter and new light O(GeV) particle. It indicates that dark sector may be complicated, and there may exist more than one light particle, for example the dark gauge boson A′ and associated dark Higgs boson h′. In this work, we discuss the scenario with A′ heavier than h′ and h′ is treated as LLP. Based on our numerical estimation, we find that the large volume neutrino telescope IceCube has the capacity to observe several tens of di-muon events per year for favorable parameters if the decay length of LLP can be comparable with the depth of atmosphere. The challenge here is how to suppress the muon background induced by cosmic rays and atmospheric neutrinos.

Detecting light long-lived particle produced by cosmic ray

We investigate the possibility of detecting light long-lived particle (LLP) produced by high energy cosmic ray colliding with atmosphere. The LLP may penetrate the atmosphere and decay into a pair of muons near/in the neutrino telescope. Such muons can be treated as the detectable signal for neutrino telescope. This study is motivated by recent cosmic electron/positron observations which suggest the existence of O(TeV) dark matter and new light O(GeV) particle. It indicates that dark sector may be complicated, and there may exist more than one light particles, for example, the dark gauge boson A′ and associated dark Higgs boson h′. In this work, we discuss the scenario with A′ heavier than h′ and h′ is treated as LLP. Based on our numerical estimation, we find that the large volume neutrino telescope IceCube has the capacity to observe several tens of di-muon events per year for favorable parameters if the decay length of LLP can be comparable with the depth of atmosphere. The challenge here is how to suppress the muon backgrounds induced by cosmic rays and atmospheric neutrinos.