Mono-top Signature from Fermionic Top-partner

We investigate mono-top signatures arising from phenomenological models of fermionic top-partners, which are degenerate in mass and decay into a bosonic dark matter candidate, either spin-0 or spin-1. Such a model provides a mono-top signature as a smoking-gun, while conventional searches with $t\bar t$ + missing transverse momentum are limited. Two such scenarios: i) a phenomenological 3rd generation extra dimensional model with excited top and electroweak sectors, and ii) a model where only a top-partner and a dark matter particle are added to the SM, are studied in the degenerate mass regime. We find that in the case of extra dimension a number of different processes give rise to effectively the same mono-top final state, and a great gain can be obtained in the sensitivity for this channel. We show that the mono-top search can explore top-partner masses up to 630 GeV and 300 GeV for the 3rd generation extra dimensional model and the minimal fermionic top-partner model, respectively, at the high luminosity LHC.