We investigate the observability of the top anomalous tqZ couplings via the trilepton signatures at the Large Hadron Collider (LHC) with the center-of-mass energy of 14 TeV. We focus on signals of the tZ associated production with the decay mode t → W + b → bℓ + ν ℓ , Z → ℓ + ℓ − , and tt production with the decay modet → Z(→ ℓ + ℓ − )q and t → bℓ + ν ℓ , where ℓ = e, µ and q reflects up and charm quarks. It is shown that at 3σ level, the FCNC top quark decay branching ratios can be probed at, respectively, about Br(t → uZ) ≤ 1.3 × 10 −4 and Br(t → cZ) ≤ 4.2 × 10 −4 with the integrated luminosity of 100 fb −1 , and probed down to Br(t → uZ) ≤ 2.2 × 10 −5 and Br(t → cZ) ≤ 8 × 10 −5 for the high-luminosity LHC with 3000 fb −

PACS 12.60.Fr -Extensions of electroweak Higgs sector PACS 13.66.Hk -Production of non-standard model particles in e − e + interactions PACS 14.80.Fd -Other charged Higgs bosons Abstract -The doubly charged Higgs bosons H ±± are the typical particles predicted in the Higgs triplet model (HTM), and the detection of them is a key to probe this model. In this letter, we focus on the study of the doubly charged Higgs bosons pair production through W W fusion process: e + e − → W * W * → H ++ H −− νe νe. We calculate the production cross-sections and compare the results with those in the s-channel pair production process: e + e − → H ++ H −− . The final signals and the relevant SM backgrounds are also examined based on two main decay modes of H ±± : H ±± → W ± W ± and H ±± → ± i ± j ( i = e, μ, τ ). Our numerical results show that, the possible signals of H ±± might be observed via this process in future high-energy e + e − linear-collider experiments.

We investigate the prospects for discovering the Flavour Changing Neutral Current (FCNC) tqh couplings via the process pp → th at the proposed High Energy Large Hadron Collider (HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh) including the realistic detector effects. The relevant SM backgrounds are considered in the cut based analysis to obtain the limits on the the branching ratios of t → qh (q = u, c), followed by the leptonic decay channel of the top quark and diphoton decay channel of the Higgs boson. The upper limits on the FCNC branching ratios at 95% confidence level (CL) and the 5σ discovery reach for the different integrated luminosities are obtained. It is shown that at the 27 TeV HE-LHC with an integrated luminosity of 15 ab −1 and at the 100 TeV FCC-hh with an integrated luminosity of 30 ab −1 , the BR(t → uh) (BR(t → ch)) can be probed, respectively, to 4.4 (6.4)×10 −5 and 1.3 (1.6)×10 −5 at the 95% CL.

PACS 12.60.Fr -Extensions of electroweak Higgs sector PACS 13.66.Hk -Production of non-standard model particles in e − e + interactions PACS 14.80.Fd -Other charged Higgs bosons Abstract -The new scalars (H ±± , H ±± and H/A) are the typical particles predicted by the Higgs Triplet Model (HTM) and the observation of these particles can be regarded as the direct evidence of the HTM. In this letter, we study three pair production processes of these scalars, i.e., e + e − → H ++ H −− , e + e − → H + H − and e + e − → HA under the non-degenerate case. The characteristic signals and relevant SM backgrounds are also discussed both in the positive scenario (M H/A > M H ± > M H ±± ) and in the negative scenario (M H/A < M H ± < M H ±± ). Our numerical results show that the enhancement of the production rates due to the cascade decays is moderate in the positive scenario but significant in the negative one. Due to the relatively small SM backgrounds, their possible signals might be detected via these processes at future ILC experiments.

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