Study of interference effects in the search for flavour-changing neutral current interactions involving the top quark and a photon or a $Z$ boson at the LHC

TL;DR

This paper investigates interference effects in top quark flavor-changing neutral current interactions involving photons or Z bosons at the LHC, assessing their impact on search sensitivities and finding these effects to be relatively small.

Contribution

It provides a detailed analysis of interference effects in FCNC top quark interactions, highlighting their limited influence compared to scale variations.

Findings

Interference effects are smaller than scale variation uncertainties.

Analysis applies to both photon and Z boson mediated processes.

Results inform future FCNC search strategies at the LHC.

Abstract

Flavour-changing neutral-current interactions of the top quark can be searched for in top-quark pair production with one top quark decaying to an up-type quark and a neutral boson, and they can be searched for in the single production of a top quark in association with such a boson. Both processes interfere if an additional up-type quark is produced in the case of single production. The impact of these interference effects on searches for flavour-changing neutral currents at the LHC is studied for the case where the neutral boson is a photon or a $Z$ boson. Interference effects are found to be smaller than variations of the renormalisation and factorisation scales.