arXiv subjects

Honglei Li

Publications and source records attributed to Honglei Li.

34 records · Page 2Linked to original sources

arXiv2023

Probing Dirac Neutrino Properties with Dilepton Signature

The neutrinophilic two Higgs doublet model is one of the simplest models to explain the origin of tiny Dirac neutrino masses. This model introduces a new Higgs doublet with eV scale VEV to naturally generate the tiny neutrino masses. Depending on the same Yukawa coupling, the neutrino oscillation patterns can be probed with the dilepton signature from the decay of charged scalar $H^\pm$. For example, the normal hierarchy predicts BR$(H^+\to e^+ν)\ll$ BR$(H^+\to μ^+ν)\approx$ BR$(H^+\to τ^+ν)\simeq0.5$ when the lightest neutrino mass is below 0.01 eV, while the inverted hierarchy predicts BR$(H^+\to e^+ν)/2\simeq$ BR$(H^+\to μ^+ν)\simeq$ BR$(H^+\to τ^+ν)\simeq0.25$. By precise measurement of BR$(H^+\to \ell^+ν)$, we are hopefully to probe the lightest neutrino mass and the atmospheric mixing angle $θ_{23}$. Through the detailed simulation of the dilepton signature and corresponding backgrounds, we find that the 3 TeV CLIC could discover $M_{H^+}\lesssim1220$ GeV for NH and $M_{H^+}\lesssim1280$ GeV for IH. Meanwhile, the future 100 TeV FCC-hh collider could probe $M_{H^+}\lesssim1810$ GeV for NH and $M_{H^+}\lesssim2060$ GeV for IH.

hep-ph↗

arXiv2023

Sterile Neutrino Portal Dark Matter from Semi-Production

In this paper, we study the feeble sterile neutrino portal dark matter under the $Z_3$ symmetry. The dark sector consists of one fermion singlet $χ$ and one scalar singlet $χ$, which transforms as $χ\to e^{i2π/3}χ, ϕ\to e^{i2π/3}ϕ$ under the $Z_3$ symmetry. Regarding fermion singlet $χ$ as the dark matter candidate, the new interaction terms $y_χϕ\bar{χ^c}χ$ and $μϕ^3/2$ could induce various new production channels. For instance, when $m_ϕ>2m_χ$, the pair decay $ϕ\toχχ$ could be the dominant channel, rather than the delayed decay $ϕ\toχν$. Another appealing scenario is when the dark sector is initially produced through the scattering process as $NN\toχχ, NN\toϕϕ,hν\toχϕ$, then the semi-production processes $N χ\toϕϕ, Nϕ\toϕχ, Nχ\toχχ$ could lead to the exponential growth of dark sector abundances. The phenomenology of sterile neutrino and the cosmological impact of the dark scalar are also considered in the $Z_3$ symmetric model.

hep-ph↗

arXiv2023

Sterile Neutrino Portal Dark Matter with $Z_3$ Symmetry

In this paper, we consider the sterile neutrino portal dark matter with $Z_3$ symmetry. This model further extends the canonical type-I seesaw with a fermion singlet $χ$ and a scalar singlet $ϕ$. Under the $Z_3$ symmetry, the dark sector transforms as $χ\to e^{i2π/3}χ, ϕ\to e^{i2π/3}ϕ$, while the standard model particles and the sterile neutrino $N$ transform trivially. Besides the interactions as $y_{N} ϕ\barχN$ and $λ_{Hϕ} (H^†H) (ϕ^†ϕ)$ allowed in the $Z_2$ symmetry, the $Z_3$ symmetry also introduces two new terms, i.e., $y_χϕ\overline{χ^{c}} χ$ and $μϕ^3/2$. These new interactions induce additional semi-annihilation processes as $χχ\to Nχ$ and $ϕϕ\to hϕ$ for WIMP dark matter. We then perform a comprehensive analysis of the phenomenology of this $Z_3$ symmetric model. Viable parameter space is explored under the constraints from dark matter relic density, Higgs invisible decay, indirect and direct detection for both fermion and scalar dark matter. We find that the semi-annihilation channels $χχ\to Nχ$ and $ϕϕ\to Nχ$ can lead to quite different phenomena from the $Z_2$ symmetric model, which provides a viable pathway to distinguish these two kinds of model.

hep-ph↗

arXiv2022

Shinning Light on Sterile Neutrino Portal Dark Matter from Cosmology and Collider

Provided the dark sector consisted of a dark scalar $ϕ$ and a dark fermion $χ$ under an exact $Z_2$ symmetry, the sterile neutrino $N$ can act as the messenger between the dark sector and standard model via the Yukawa coupling $λ_{ds} \barχϕN$. In this paper, we focus on the specific scenario $m_N>m_ϕ+m_χ$ with $χ$ being a FIMP dark matter. The decay width of dark scalar $ϕ$ is doubly suppressed by the smallness of Yukawa coupling $λ_{ds}$ and mixing angle $θ$. The delayed decay $ϕ\toχν$ will have a great impact on cosmological observables such as the Big Bang Nucleosynthesis, the Cosmic Microwave Background anisotropy power spectra, the effective number of relativistic neutrino species $N_{\rm eff}$ and the energetic neutrino flux. Meanwhile, the sterile neutrino can generate displaced vertex signature at colliders when $m_N<m_W$. The dark scalar $ϕ$ will also induce measurable Higgs invisible decay for relatively large quartic coupling. A comprehensive analysis of constraints from cosmology and collider is performed in this paper. We find that almost the whole parameter space with $m_N<m_W$ is under the reach of future experiments.

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arXiv2022

Unraveling the Scotogenic Model at Muon Collider

The Scotogenic model extends the standard model with three singlet fermion $N_i$ and one inert doublet scalar $η$ to address the common origin of tiny neutrino mass and dark matter. For fermion dark matter $N_1$, a hierarchical Yukawa structure $|y_{1e}|\ll|y_{1μ}|\sim|y_{1τ}|\sim\mathcal{O}(1)$ is usually favored to satisfy constraints from lepton flavor violation and relic density. Such large $μ$-related Yukawa coupling would greatly enhance the pair production of charged scalar $η^\pm$ at the muon collider. In this paper, we investigate the dilepton signature of the Scotogenic model at a 14 TeV muon collider. For the dimuon signature $μ^+μ^-+/ \hspace{-0.65em} E_T$, we find that most viable samples can be probed with $200~\text{fb}^{-1}$ data. The ditau signature $τ^+τ^-+/ \hspace{-0.65em}E_T$ is usually less promising but is important to probe the small $|y_{1μ}|$ region. The mono-photon signature $γ+/ \hspace{-0.65em} E_T$ could also probe the compressed mass region $M_1\lesssim M_{η^\pm}$. Masses of charged scalar $η^\pm$ and dark matter $N_1$ can be further extracted by a binned likelihood fit of the dilepton energy.

hep-ph↗

arXiv2022

MSSM Under Higgs Factories

The high precision measurements of the Higgs mass and couplings at the future Higgs factories are sensitive to the parameter space of the Minimal Supersymmetric Standard Model (MSSM). Focused on the dominant stop sector contributions, we study the implication of the Higgs precision measurements on MSSM using multi-variable $χ^2$ fit. The results show nice complementarity between the indirect searches at Higgs factories and the direct searches at the current LHC program.

hep-ph↗

arXiv2022

Exotic Higgs Decays in the Type-II 2HDMs at Current and Future pp Colliders

The exotic decay modes of non-Standard Model Higgses can serve as powerful search channels to explore the parameter space of extended Higgs sectors. In this Snowmass contribution, we illustrate this using the Two-Higgs Doublet Model (2HDM) as an example. We first review the current experimental constraints on the parameter space of a Type-II 2HDM arising from existing searches for the exotic Higgs decay mode $A/H\rightarrow HZ/AZ$. We then present the sensitivity of future colliders to discover addition Higgs bosons using the exotic decay channels $A\rightarrow HZ$, $A\rightarrow H^\pm W^\mp$ and $H^\pm\rightarrow H W^\pm$. We find that a 100 TeV collider can probe almost the entire region of the Type-II 2HDM parameter space that survives current theoretical and experimental constraints and would therefore be an ideal machine to search for heavier Higgses in hierarchical scalar sectors.

hep-ph↗

arXiv2022

Sterile Neutrino Portal Dark Matter in $ν$THDM

In this paper, we propose the sterile neutrino portal dark matter in $ν$THDM. This model can naturally generate tiny neutrino mass with the neutrinophilic scalar doublet $Φ_ν$ and sterile neutrinos $N$ around TeV scale. Charged under a $Z_2$ symmetry, one Dirac fermion singlet $χ$ and one scalar singlet $ϕ$ are further introduced in the dark sector. The sterile neutrinos $N$ are the mediators between the DM and SM. Depending on the coupling strength, the DM can be either WIMP or FIMP. For the WIMP scenario, pair annihilation of DM into $NN$ is the key channel to satisfy various bounds, which could be tested at indirect detection experiments. For the FIMP scenario, besides the direct production of DM from freeze-in mechanism, contributions from late decay of NLSP is also important. When sterile neutrinos are heavier than the dark sector, NLSP is long-lived due to tiny mixing angle between sterile and light neutrinos. Constrains from free-streaming length, CMB, BBN and neutrino experiments are considered.

hep-ph↗

arXiv2021

Investigating the $Z^\prime$ gauge boson at the future lepton colliders

$Z^\prime$ boson as a new gauge boson has been proposed in many new physics models. The interactions of $Z^\prime$ coupling to fermions are detailed studied at the large hadron collider. A $Z^\prime$ with the mass of a few TeV has been excluded in some special models. The future lepton colliders will focus on the studies of Higgs physics which provide the advantage to investigate the interactions of Higgs boson with the new gauge bosons. We investigate the $Z^\prime ZH$ interaction via the process of $e^+e^- \to Z^\prime/Z \to ZH \to l^+l^- b \bar{b}$. The angular distribution of the final leptons decaying from the $Z$-boson is related to the mixing of $Z^\prime$-$Z$ and the mass of $Z^\prime$. The forward-backward asymmetry has been proposed as an observable to investigate the $Z^\prime$-$Z$ mixing. The angular distributions change significantly with some special beam polarization comparing to the unpolarized condition.

hep-ph↗

arXiv2021

$D^*$ meson production in jet from combination of charm quark with light one

In the framework of the perturbative Quantum Chromodynamics factorization, the cross section of the heavy meson production via the combination of a heavy quark with a light one can be factorized to be the convolution of the combination matrix element, the light quark distribution function, and the hard partonic sub-cross section of the heavy quark production. The partonic distribution and the combination matrix element are functions of a scaling variable, respectively, which is the momentum fraction of the corresponding quark with respect to the heavy meson. We studied the $D^{*\pm}$ production in jet via combination in pp collision at the LHC. Our calculation can be summed with the fragmentation contribution, and the total result is comparable with the experimental data. The combination matrix elements can be further studied in various hadron production processes.

hep-ph↗

arXiv2020

MSSM at future Higgs factories

In this work, we study the implication of Higgs precision measurements at future Higgs factories on the MSSM parameter space, focusing on the dominant stop sector contributions. We perform a multi-variable fit to both the signal strength for various Higgs decay channels at Higgs factories and the Higgs mass. The chi-square fit results show sensitivity to mA, tan beta, stop mass parameter mSUSY as well as the stop left-right mixing parameter Xt. We also study the impact of the Higgs mass prediction on the MSSM and compare the sensitivities of different Higgs factories.

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arXiv2020

Consortium Blockchain for Security and Privacy-Preserving in E-government Systems

Since its inception as a solution for secure cryptocurrencies sharing in 2008, the blockchain technology has now become one of the core technologies for secure data sharing and storage over trustless and decentralised peer-to-peer systems. E-government is amongst the systems that stores sensitive information about citizens, businesses and other affiliates, and therefore becomes the target of cyber attackers. The existing e-government systems are centralised and thus subject to single point of failure. This paper proposes a secure and decentralised e-government system based on the consortium blockchain technology, which is a semi-public and decentralised blockchain system consisting of a group of pre-selected entities or organisations in charge of consensus and decisions making for the benefit of the whole network of peers. In addition, a number of e-government nodes are pre-selected to perform the tasks of user and transaction validation before being added to the blockchain network. Accordingly, e-government users of the consortium blockchain network are given the rights to create, submit, access, and review transactions. Performance evaluation on single transaction time and transactions processed per second demonstrate the practicability of the proposed consortium blockchain-based e-government system for secure information sharing amongst all stakeholders.

cs.CR↗

arXiv2018

Exotic Higgs Decays in Type-II 2HDMs at the LHC and Future 100 TeV Hadron Colliders

The exotic decay modes of non-Standard Model (SM) Higgses in models with extended Higgs sectors have the potential to serve as powerful search channels to explore the space of Two-Higgs Doublet Models (2HDMs) that cannot be studied effectively using conventional decay channels. Once kinematically allowed, heavy Higgses could decay into pairs of light non-SM Higgses, or a non-SM Higgs and a SM gauge boson, with branching fractions that dominate those of the conventional decay modes to SM particles. In this study, we focus on the prospects of probing exotic decay channels at the LHC and a future 100 TeV \emph{pp} collider in the context of Type-II 2HDMs. We study the three prominent exotic decay channels, A -> HZ, A -> H^+ W and H^+ -> HW, and find that a 100-TeV pp collider can probe the entire region of the Type-II 2HDM parameter space that survives current theoretical and experimental constraints with exotic decay branching fraction > 20%.

hep-ph↗

arXiv2018

New physics implication of Higgs precision measurements

Studying the properties of the Higgs boson can be an important window to explore the physics beyond the Standard Model (SM). In this work, we present studies on the implications of the Higgs precision measurements at future Higgs Factories. We perform a global fit to various Higgs search channels to obtain the 95 % C.L. constraints on the model parameter spaces of Two Higgs Double Model (2HDM) and Minimal Supersymmetric Standard Model (MSSM). In the 2HDM, we analyze tree level effects as well as one-loop contributions from the heavy Higgs bosons. The strong constraints on $\cos(β-α)$, heavy Higgs masses and their mass splitting are complementary to direct search of the LHC as well as possible future Z pole precision measurements. For the MSSM, we study both the Higgs couplings and mass precisions. The constraints on the CP-odd Higgs mass $m_A$ and stop mass scale $m_{SUSY}$ can be complementary to the direct search of HL-LHC. We also compare the sensitivity of various future Higgs factories, namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC).

hep-ph↗

arXiv2017

Learning from Higgs Physics at Future Higgs Factories

Future Higgs factories can reach impressive precision on Higgs property measurements. In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explored its sensitivity to new physics models at the electron-positron colliders. In particular, we studied two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weakly-interacting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong interacting models as examples of strong dynamics. We performed a global fit to various Higgs search channels to obtain the 95% C.L. constraints on the model parameter space. In the SM with a singlet extension, we obtained the limits on the singlet-doublet mixing angle sin(theta), as well as the more general Wilson coefficients of the induced higher dimensional operators. In the 2HDM, we analyzed tree level effects in tan(beta) vs. cos(beta-alpha) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for different types of 2HDM. In strong dynamics models, we obtained lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish different models. We also compared the sensitivity of various future Higgs factories, namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC).

hep-ph↗

arXiv2010

Sbottom Signature of the Supersymmetric Golden Region

The experimental search limit on the Higgs boson mass points to a "golden region" in the Minimal Supersymmetric Standard Model parameter space in which the fine-tuning in the electroweak sector is minimized. One of the sbottoms is relatively light since its mass parameter is related to that of the stop. The decay products of the light sbottom typically include a W boson and a b jet. We studied the pair production of the light sbottoms at the Large Hadron Collider and examined its discovery potential via collider signature of 4 jets + 1 lepton + missing E_T. We analyzed the Standard Model backgrounds for this channel and developed a set of cuts to identify the signal and suppress the backgrounds. We showed that with 100 fb^{-1} integrated luminosity, a significant level of 5 sigma could be reached for the light sbottom discovery at the LHC.

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