We propose a two-Higgs-doublet model in which one Higgs doublet has the same interactions with fermions as the SM, and another Higgs doublet only has the $μ$-$τ$ LFV interactions. Assuming that the Yukawa matrices are real and symmetric, we impose various relevant theoretical and experimental constraints, and find that the excesses of muon $g-2$ and lepton flavour universality in the $τ$ decays can be simultaneously explained in the region of small mass splittings between the heavy CP-even Higgs and the CP-odd Higgs ($m_A > m_H$). The multi-lepton event searches at the LHC can sizably reduce the mass ranges of extra Higgses, and $m_H$ is required to be larger than 560 GeV.
We propose a minimal model which accommodates the long-standing anomaly of muon magnetic moment based on abelian discrete flavor symmetries. The standard model is extended by scalar doublets charged under a $Z_n$ lepton flavor symmetry. In these models, a large contribution to the muon magnetic moment can be obtained by the chirality enhancement from new scalar mediated diagrams without conflicting with the flavor symmetry. Thanks to the lepton flavor symmetry, these models automatically forbid lepton flavor violation. The minimal model is based on $Z_4$ symmetry with only one extra scalar dou…
We examine the possibilities of accommodating the muon $g-2$ anomaly reported by Fermilab in the 2HDM with a discrete $Z_4$ symmetry in which an inert Higgs doublet field ($H,~A,~H^\pm$) has the lepton flavor violation $μ$-$τ$ interactions. We study the case of light $H$ (5 GeV $<m_H<$ 115 GeV) and assume the Yukawa matrices to be real and symmetrical. Considering relevant theoretical and experimental constraints, especially for the multi-lepton searches at the LHC, we find the muon $g-2$ anomaly can be explained within $2σ$ range in the region of 5 GeV $<m_H<20$ GeV, 130 GeV $< m_A~(m_{H^\pm}…
In this work, we introduce an extra singlet pseudoscalar into the Type-III two Higgs doublet model (2HDM) which is supposed to solve a series of problems in the modern particle-cosmology. With existence of a light pseudoscalar, the $h\rightarrowμτ$ excess measured at CMS and as well as the $(g-2)_μ$ anomaly could be simultaneously explained within certain parameter spaces that can also tolerate the data on the flavor-violating processes $τ\rightarrowμγ$ and Higgs decay gained at LHC. Within the same parameter spaces, the DM relic abundance is well accounted. Moreover, the recently observed Gal…
Combining the multi-lepton searches at the LHC, we study the possibilities of accommodating the new data of muon and electron $g-2$ anomalies in the lepton-specific inert two-Higgs-doublet model. We take the heavy CP-even Higgs as the 125 GeV Higgs, and find the muon and electron $g-2$ anomalies can be explained simultaneously in the region of 5 GeV $< m_h<60$ GeV, 200 GeV $<m_A< 620$ GeV, 190 GeV $<m_{H^\pm}< 620$ GeV for appropriate Yukawa couplings between leptons and inert Higgs. Meanwhile, the model can give a better fit to the data of lepton universality in $τ$ decays than the SM. Furthe…
We propose a novel possibility to detect a very distinctive signal with more than four muons originating from pair-produced vector-like leptons decaying to a muon-philic $Z^\prime$ boson. These new particles are good candidates to explain the anomalies in the muon anomalous magnetic moment and the $b\to s\ell\ell$ processes. The doublet (singlet) vector-like leptons lighter than 1.3 (1.0) TeV are excluded by the latest data at the LHC if $\mathrm{BR}(E\to Z^\prime μ) = 1$. We also show that the excess in the signal region with more than five leptons can be explained by this scenario if the vec…
Imposing the theoretical constraints from vacuum stability, unitarity and perturbativity as well as the experimental constraints from the electroweak precision data, flavor observables and the non-observation of additional Higgs at collider, we study the implications of available Higgs signals on a two-Higgs-doublet model with the alignment of the down-type quarks and charged lepton Yukawa coupling matrices. Compared to the four traditional types of two-Higgs-doublet models, the model has two additional mixing angles $θ_d$ and $θ_l$ in the down-type quark and charged lepton Yukawa interactions…
We examine the parameter space of two-Higgs-doublet model of type-II after imposing the relevant theoretical and experimental constraints from the precision electroweak data, $B$-meson decays, the LHC run-I and run-II data. We find that the searches for Higgs via the $τ\barτ,~WW,~ZZ,γγ,~hh,~hZ,~HZ,~AZ$ channels can give strong constraints on the CP-odd Higgs $A$ and heavy CP-even Higgs $H$, and the parameter space excluded by each channel is respectively carved out in detail. The surviving samples are discussed in two different of regions: (i) In the SM-like coupling region of the 125 GeV Higg…
Motivated by experimental hints on the possibility of deviating from the SM predictions for the 2-photon decay rate of the 125 GeV SM-like scalar boson h, an analysis of this rate in the framework of the Inert Doublet Model is presented. Regions in the parameter space where the 2-photon decay rate is enhanced were found. The resulting regions are confronted with the allowed values of the Dark Matter (DM) particle's mass. Constraints on the masses of the charged scalar and the DM particle, and scalar couplings are presented.
Two models that extend the particle content of the SM and provide dark matter candidates, namely the Inert Doublet Model and the Two-Higgs Doublet model with additional pseudoscalar, are confronted with current experimental and theoretical constraints and predictions for production cross sections for various standard pair-production modes within these models at future lepton colliders are presented.
Properties of the Z_2-symmetric Two Higgs Doublet Models (2HDM) are discussed and confronted with new LHC data for a 125 GeV Higgs particle. The particle discovered at LHC in 2012 has properties expected for it in the Standard Model (SM), with a possible enhancement in the two-photon channel. SM-like Higgs scenarios can be realized in the Two Higgs Doublet Models with Z_2 (D) symmetry within the normal Mixed Model (with scalar sector as in MSSM) and the Inert Doublet Model (IDM), where a good Dark Matter (DM) candidate is present. Here we discuss both of the models.
We investigated a general framework of the Standard Model with two Higgs doublets (2HDSM) with suppressed flavor-changing neutral currents (FCNC's). Loop-induced FCNC (and CP-violating) effects, when confronted with experimental constraints for the $K$-$\bar K$, $B$-$\bar B$ and $D$-$\bar D$ mixing and for the $(b \to s γ)$ decay, provide us with constraints on the values of the dominant Yukawa couplings of the charged Higgs, i.e., the values of the couplings of $H^{\pm}$ to $t$ and $b$ quarks. Once these {\it low} energy experimental data relevant for the mixings and for the mentioned decay, …
An improved analysis of the diphoton decay rate of the Higgs boson in the Inert Doublet Model is presented together with critical discussion of the results existing in the literature. For Higgs boson mass M_h equal 125 GeV, and taking into account the following constraints: vacuum stability, existence of the Inert vacuum, perturbative unitarity, electroweak precision tests and the LEP bounds, we found regions in the parameter space where the diphoton rate is enhanced. The resulting regions were confronted with the allowed values of the Dark Matter mass. We found that significant enhancement in…
We {works done in collaboration with C.S.Kim, Yonsei Univ., Seoul, Korea} present some properties of the SM with two Higgs doublets. Unlike the minimal SM, the Yukawa couplings (in the usual ``type II'' model) converge with the increasing energy to flavor democracy (FD), i.e.~to common values, in a specific flavor basis. This may represent a possible signal of some new, (almost) flavor-blind physics beyond the SM. When imposing the assumption of equality of the corresponding quark and leptonic Yukawa couplings at high transition energies, we can estimate the physical mass of the tau-neutrino a…
In the framework of type-II two-Higgs-doublet model with a scalar dark matter ($S$), we examine the wrong sign Yukawa coupling of the 125 GeV Higgs which is the only portal between the dark matter and SM sectors. After imposing the constraints from the Higgs searches at the LHC and dark matter experiments, we obtain some interesting observables: (i) The theory, oblique parameters, and the Higgs searches at the LHC can impose stringent constraints on $\tanβ$ in the case of the wrong sign Yukawa coupling of the 125 GeV Higgs. For example, for $m_H=600$ GeV and 140 GeV $<m_A<200$ GeV, $\tanβ$ is …
Constraining $A\to ZH$ with $H\to t\bar t$ in the Low-Mass Region
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；Universität Zürich（苏黎世大学）；University of the Witwatersrand（威特沃特斯兰德大学）；Indian Institute of Science Education and Research Pune（印度科学教育研究所浦那分校）；Institute of High Energy Physics（高能物理研究所）
Searching for charged Higgs bosons in top decays via the $t^*b$ channel
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；INFN, Sezione di Bologna（意大利国家核物理研究所博洛尼分所）；Universitat Autònoma de Barcelona（巴塞罗那自治大学）；ICREA, Institució Catalana de Recerca i Estudis Avançats（加泰罗尼亚高级研究学院）；Sorbonne Université et CNRS（索邦大学与法国国家科学研究中心）；ETH Zürich（苏黎世联邦理工学院）
研究通过$t\to H^\pm b$，$H^\pm\to t^*b$过程寻找带电希格斯玻色子，利用顶夸克 - 反顶夸克产生和衰变产生的类似$t\bar t b\bar b$末态，通过重新解释ATLAS测量进行限制，给出分支比乘积限制并在多种模型情形下解释，确立其为补充探测手段。
