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arXiv · 1408.2090

Single top quark production as a probe of anomalous $tqγ$ and $tqZ$ couplings at the FCC-ee

Hamzeh Khanpour·Sara Khatibi·Morteza Khatiri Yanehsari·Mojtaba Mohammadi Najafabadi
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Abstract

In this paper, a detailed study to probe the top quark Flavour-Changing Neutral Currents (FCNC) $tqγ$ and $tqZ$ at the future $e^{-}e^{+}$ collider FCC-ee in three different center-of-mass energies of 240, 350 and 500 GeV is presented. A set of useful variables are proposed and used in a multivariate technique to separate signal $e^- e^+ \rightarrow Z/γ\rightarrow t \bar{q} ~ ( \bar{t} q )$ from standard model background processes. The study includes a fast detector simulation based on the {\sc delphes} package to consider the detector effects. The $3 σ$ discovery regions and the upper limits on the FCNC branching ratios at 95\% confidence level (CL) in terms of the integrated luminosity are presented. It is shown that with 300 fb$^{-1}$ of integrated luminosity of data, FCC-ee would be able to exclude the effective coupling strengths above ${\cal O} (10^{-4}-10^{-5})$ which is corresponding to branching fraction of ${\cal O}(0.01-0.001)$\%. We show that moving to a high-luminosity regime leads to a significant improvement on the upper bounds on the top quark FCNC couplings to a photon or a $Z$ boson.

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Hamzeh Khanpour, Sara Khatibi, Morteza Khatiri Yanehsari, Mojtaba Mohammadi Najafabadi. 2017-03-29. Single top quark production as a probe of anomalous $tqγ$ and $tqZ$ couplings at the FCC-ee. https://doi.org/10.1016/j.physletb.2017.10.047

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