Probing the Top Quark Flavour-Changing Neutral Current at a Future Electron-Positron Collider

TL;DR

This paper assesses the potential of a future electron-positron collider to detect rare top quark flavor-changing neutral current processes involving gluons, using multivariate analysis to distinguish signal from background.

Contribution

It introduces a detailed sensitivity study for top FCNC interactions at future colliders, including analysis methods and projected limits on anomalous couplings.

Findings

Projected 95% CL limits on top FCNC couplings at various energies.

Demonstrates effectiveness of multivariate analysis in separating signal from background.

Provides insights into collider capabilities for rare top quark decay detection.

Abstract

We present a study to examine the sensitivity of a future $e^{-} e^{+}$ collider to the anomalous top flavour-changing neutral current (FCNC) to the gluon. To separate signal from background a multivariate analysis is performed on top-quark pair and background events, where one top quark is considered to follow the dominant Standard Model (SM) decay, $t \rightarrow Wb$, and the other top decays through FCNC, $t\rightarrow qg$, where $q$ is a $u-$ or a $c-$quark. The analysis of fully-hadronic FCNC decay of the $t \bar{t}$ pair is also presented. The $95\%$ confidence level limits on the top-quark anomalous couplings are obtained for different values of the center-of-mass energies and integrated luminosities.