Study of ATLAS Sensitivity to FCNC TOP Quark Decay t--> Zq

TL;DR

This study evaluates the ATLAS experiment's ability to detect rare top-quark decays via flavor-changing neutral currents, specifically t→Zq, at 14 TeV, analyzing two decay modes and estimating the minimal branching ratios detectable.

Contribution

It provides a detailed simulation-based analysis of ATLAS sensitivity to t→Zq decays, including background analysis and detection thresholds for different decay modes.

Findings

Detection of t→Zq with branching ratios as low as 1.1×10^{-4} in leptonic mode.

Detection of t→Zq with branching ratios as low as 2.3×10^{-4} in hadronic mode.

Background processes analyzed include Z+jets, Zw, and t-tbar.

Abstract

The sensitivity of ATLAS experiment to the top-quark rare decay via flavor- changing neutral currents t \to Zq (q represents c and u quarks) have been studied at \sqrt{s}= 14 TeV in two decay modes: 1. The pure leptonic decay of gauge bosons: t\bar{t} \to ZqWb \to l^{+} l^{-} j l^{+-} nu j_{b} (l=e, mu) 2. The leptonic decay of Z bosons and hadronic decay of W bosons t\bar{t} \to ZqWb \to l^{+} l^{-} jjjj_{b} (l=e, mu) The dominant backgrounds Z-jets, Zw and t\bar{t} has been analysed. The signal and backgrounds were generated via PYTHIA 5.7, simulated and analysed using ATLFAST 2.14. A branching ratio for t \to Zq as low as 1.1x1-^{4} for the leptonic mode and 2.3x10^{4} for hadronic mode could be discovered at the 5\sigma level with an integrated luminosity of 10^{5} pb^{-1}.