[en] Considering the constraints of the lepton flavor violating (LFV) processes μ→3e and τ→3μ on the LFV couplings Z^′ℓ_iℓ_j, in the contexts of the E₆ models, the left–right (LR) models, the “alternative” left–right (ALR) models and the 331 models, we investigate the contributions of the extra gauge boson Z^′ to the decay rates of the processes ℓ_i→ℓ_jν_ℓν_ℓ, τ→μP and P→μe with P=π⁰,η and η^′. Our numerical results show that the maximal values of the branching ratios for these processes are not dependent on the Z^′ mass M_Z^′ at leader order. The extra gauge boson Z_X^′ predicted by the E₆ models can make the maximum value of the branching ratio Br(τ→μν_ℓν_ℓ) reach 1.1×10⁻⁷. All Z^′ models considered in this paper can produce significant contributions to the process τ→μP. However, the value of Br(P→μe) is far below its corresponding experimental upper bound

[en] Taking into account of the constraints on the relevant parameters from the muon anomalous magnetic moment, we consider the contributions of the vector bileptons V^± and U^±± predicted by the reduced minimal 331 model to the Higgs decay channels h→γγ and Zγ. Our numerical results show that the vector bileptons can enhance the partial width Γ(h→γγ), while reduce the partial width Γ(h→Zγ), which are anti-correlated. With reasonable values of the relevant free parameters, the vector bileptons can explain the LHC data for the γγ signal. If the CMS data persists, the values of the free parameters λ₂ and λ₃ should be severe constrained

[en] The littlest Higgs (LH) model predicts the existence of the doubly charged scalars Φ^±±, which generally have large flavor changing couplings to leptons. We calculate the contributions of Φ^±± to the lepton flavor violating (LFV) processes l_i→l_jγ and l_i→l_jl_kl_k, and we compare our numerical results with the current experimental upper limits on these processes. We find that some of these processes can give severe constraints on the coupling constant Y_ij and the mass parameter M_Φ. Taking into account the constraints on these free parameters, we further discuss the possible lepton flavor violating signals of Φ^±± at high energy linear e⁺e^- collider (ILC) experiments. Our numerical results show that the possible signals of Φ^±± might be detected via the subprocesses e^±e^±→l^±l^± in future ILC experiments. (orig.)

[en] Considering the superior performances of the future e-p colliders, LHeC and FCC-eh, we discuss the feasibility of detecting the extra neutral scalar h${}_2$ and the light gauge boson Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$, which are predicted by the U(1)${}_{L_{\mathrm{\mu <!--\; ??\; -->}}-<!--\; ???\; -->L_{\mathrm{\tau <!--\; ??\; -->}}}$ model. Taking into account the experimental constraints on the relevant free parameters, we consider all possible production channels of h${}_2$ and Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$ at e-p colliders and further investigate their observability through the optimal channels in the case of the beam polarization P(e${}^{-<!--\; ???\; -->}$)=-0.8. We find that the signal significance above 5σ of h${}_2$ as well as Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$ detecting can be achieved via e${}^{-<!--\; ???\; -->}$p $\to <!--\; ???\; -->$ e${}^{-<!--\; ???\; -->}$ jh${}_2$ ($\to <!--\; ???\; -->$ Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$ Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$) $\to <!--\; ???\; -->$ e${}^{-<!--\; ???\; -->}$ j+ $\text{⧸}{E}_{\mathrm{\tau <!--\; ??\; -->}}$ process and a 5σ sensitivity of Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$ detecting can be gained via e${}^{-<!--\; ???\; -->}$p $\to <!--\; ???\; -->$ e${}^{-<!--\; ???\; -->}$ jh${}_1$ ($\to <!--\; ???\; -->$ Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$ Z${}_{\mathrm{\mu <!--\; ??\; -->}\mathrm{\tau <!--\; ??\; -->}}$) $\to <!--\; ???\; -->$ e${}^{-<!--\; ???\; -->}$ j+ $\text{⧸}{E}_{\mathrm{\tau <!--\; ??\; -->}}$ process at e-p colliders with appropriate parameter values and a designed integrated luminosity. However, the signals of h${}_2$ decays into pair of SM particles are difficult to be detected.

[en] In the framework of little Higgs models and the three-site Higgsless model, we discuss the contributions of the new charged gauge boson W' to the process eq→νq' and the possibility of detecting W' via this process in future high energy linear e⁺e^- collider (ILC) and ep collider (THERA) experiments. Our numerical results show that the process eq→νq' is rather sensitive to the coupling W'ff', and one can use this process to distinguish different new physics models in future ILC and THERA experiments. (orig.)

[en] The new particles predicted by the topcolor-assisted technicolor (TC2) model and the littlest Higgs model with T-parity (called LHT model) can induce the lepton flavor violation (LFV) couplings at tree level or one loop level, which might generate large contributions to some LFV processes. Taking into account the constraints of the experimental data on the relevant free parameters, we calculate the branching ratios of the LFV decay processes τ^-→μ^-P₁P₂ with P₁ P₂=π⁺π^-, K⁺ K^- and K⁰ anti K⁰ in the context of these two kinds of new physics models. We find that the TC2 model and the LHT model can indeed produce significant contributions to some of these LFV decay processes. (orig.)

[en] The littlest Higgs model with T-parity predicts the existence of the T-odd particles, which can only be produced in pairs. We consider pair production of the T-odd leptons in a future high energy linear e⁺e^- collider (ILC). Our numerical results show that, as long as the T-odd leptons are not too heavy, they can be copiously produced and their possible signals might be detected via the processes e⁺e^-→anti L_iL_j in future ILC experiments. (orig.)

[en] In the context of the littlest Higgs (LH) model, we study the process e⁺e^-→t anti t. We find that the new gauge bosons Z_H and B_H can produce significant correction effects on this process, which can be further enhanced by suitably polarized beams. In most of the parameter space preferred by the electroweak precision data, the absolute value of the relative correction parameter R_BH is larger than 5 %. As long as 1TeV≤M_ZH≤1.5 TeV and 0.3≤c≤0.5, the absolute value of the relative correction parameter R_ZH is larger than 5%. With reasonable values of the parameters of the LH model, the possible signals of the new gauge bosons B_H and Z_H can be detected via the process e⁺e^-→t anti t in the future LC experiments with the CM energy √(S) = 800 GeV. B_H exchange and Z_H exchange can generate significantly corrections to the forward-backward asymmetry A_FB(t anti t) only in a small part of the parameter space. (orig.)

[en] One kind of particularly interesting pseudoscalar particles, called axion-like particles (ALPs), have rich physical phenomenology at high- and low-energy collider experiments. After discussing most of single production channels of ALP at electron-positron colliders, we investigate the possibility of detecting this kind of new particles through the W${}^{+}$W${}^{-<!--\; ???\; -->}$ fusion process $e^{+}{e}^{-<!--\; ???\; -->}$ → ${\stackrel{¯<!--\; ??\; -->}{\mathrm{\nu <!--\; ??\; -->}}}_e{\mathrm{\nu <!--\; ??\; -->}}_e$a (→ γγ) at the CLIC. The 3σ and 5σ bounds on the ALP parameter space at the three energy stages of the CLIC are obtained. We find that the bounds given by the CLIC are complementary to the existing experiments exclusion regions.

[en] The light axigluon model can explain the Tevatron tt-macron forward-backward asymmetry and at the same time satisfy the constraints from the electroweak precision measurement and the ATLAS and CMS data, which induces the flavor changing (FC) couplings of axigluon with the SM and new quarks. We investigate the effects of these FC couplings on the s- and t-channel single top productions at the LHC and the FC decays Z→b-macrons+bs-macron, t→cγ and cg. Our numerical results show that the light axigluon can give significantly contributions to single top production and the rare top decays t→cγ and cg