Down type iso-singlet quarks at the HL-LHC and FCC-hh

We study the discovery potential of down type iso-singlet quarks, D, predicted by the $E_6$ GUT model in the ${pp\rightarrow D\bar{D}\rightarrow ZZd\bar{d} \rightarrow \ell ^+\ell ^-\ell ^+\ell ^- d\bar{d}}$ channel, at the HL-LHC and FCC-hh colliders. The analysis is performed using a high level analysis description language and its runtime interpreter. The study shows that, using solely this channel, HL-LHC can discover D quarks up to a mass of 730 GeV whereas FCC-hh up to 2980 GeV with data collected in their complete run periods.