Study of ATLAS sensitivity to FCNC top decays

TL;DR

This paper evaluates ATLAS's ability to detect rare top quark decays via FCNC processes at the LHC, comparing analysis methods and establishing sensitivity limits for these elusive decay channels.

Contribution

It provides a comprehensive study of ATLAS sensitivity to various FCNC top decays, including analysis comparisons and new limits on branching ratios.

Findings

Sensitivity to FCNC branching ratios at 5sigma significance.

95% CL limits on FCNC decay branching ratios.

Comparison of analysis techniques for different FCNC modes.

Abstract

The ATLAS experiment sensitivity to top quark Flavour Changing Neutral Current (FCNC) decays was studied at LHC using ttbar events. While one of the top quarks is expected to follow the dominant Standard Model decay t->bW, the other decays through a FCNC channel, i.e. t-> Z u(c), t-> gamma u(c) or t-> g u(c). Different types of analyses, applied to each FCNC decay mode, were compared. The FCNC branching ratio sensitivity (assuming a 5sigma signal significance) and 95% confidence level limits on the branching ratios (in the hypothesis of signal absence) were obtained.