## Probing top quark FCNC tq$$\gamma$$ and tqZ couplings at future electron-proton colliders.(English)Zbl 1430.81083

Summary: The top quark flavor changing neutral current (FCNC) processes are extremely suppressed within the Standard Model (SM) of particle physics. However, they could be enhanced in a new physics model Beyond the Standard Model (BSM). The top quark FCNC interactions would be a good test of new physics at present and future colliders. Within the framework of the BSM models, these interactions can be described by an effective Lagrangian. In this work, we study tq $$\gamma$$ and tqZ effective FCNC interaction vertices through the process $$e^- p \rightarrow e^- W q + X$$ at future electron proton colliders, projected as Large Hadron electron Collider (LHeC) and Future Circular Collider-hadron electron (FCC-he). The cross sections for the signal have been calculated for different values of parameters $$\lambda_q$$ for tq $$\gamma$$ vertices and $$\kappa_q$$ for tqZ vertices. Taking into account the relevant background we estimate the attainable range of signal parameters as a function of the integrated luminosity and present contour plots of couplings for different significance levels including detector simulation. We find the sensitivities to the branching ratios $$(B R(t \rightarrow q \gamma) = 7.5 \times 10^{- 6}, B R(t \rightarrow q Z) = 3.5 \times 10^{- 5})$$ and $$(B R(t \rightarrow q \gamma) = 8.5 \times 10^{- 7}, B R(t \rightarrow q Z) = 6.0 \times 10^{- 6})$$ for an integrated luminosity of $$2 \text{ab}^{- 1}$$ at LHeC and FCC-he, respectively.

### MSC:

 81V05 Strong interaction, including quantum chromodynamics 81V22 Unified quantum theories 81V35 Nuclear physics 81U35 Inelastic and multichannel quantum scattering

### Software:

PYTHIA8; FeynRules
Full Text:

### References:

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