NIKHEF-2017-069
MCNET-17-24
arXiv:1712.06332
Eur.Phys.J. C78 (2018) 214

by: Papaefstathiou, Andreas (Amsterdam U.) et al.

Abstract:
We investigate extremely rare top quark decays at a future proton–proton collider with centre-of-mass energy of 100 TeV. We focus on two decay modes: radiative decay with a Z boson, $t \rightarrow b WZ$ , and flavour-changing neutral decay with a Higgs boson, $t \rightarrow h c$ , the former being kinematically suppressed with a branching ratio of ${\mathscr {O}}(10^{-6})$ (Altarelli et al., Phys Lett B 502:125–132, 2001), and the latter highly loop-suppressed, with a branching ratio of ${\mathscr {O}}(10^{-15})$ (Aguilar-Saavedra, Acta Phys Polon B 35:2695–2710, 2004). We find that $t \rightarrow b WZ$ will be very challenging to observe in top quark pair production, even within well-motivated beyond-the-standard model scenarios. For the mode $t\rightarrow h c$ we find a stronger sensitivity than that obtained by any future LHC measurement by at least one order of magnitude.