a heavy $Z^\prime$ boson [@Altarelli:1989ff] via $pp \rightarrow Z^\prime \rightarrow t\bar{t}$, also with semileptonic decays of the top quarks. As a benchmark for this study, we select the $Z^\prime$ mass to be $2$ TeV with a width of $89.6$ GeV. A transverse momentum cut of $p_T > 500$ GeV is applied directly to the top quarks at generator level, for both signal and background events.

Following the concept of reconstructing highly boosted top quarks with fat jets [@Plehn:2011tg; @Plehn:2011sj], the hadrons and non-isolated leptons from the event are initially clustered into jets using the Cambridge-Aachen algorithm [@Dokshitzer:1997in] with a radius of $R=1.0$. The constituents of the two hardest fat jets are then reclustered into jets using the $k_T$ algorithm with $R=0.2$, implemented in <span style="font-variant:small-caps;">FastJet</span> [@Cacciari:2011ma]. Jets are required to have $p_T > 30$ GeV and are $b$-tagged through their association to a $B$-meson. Isolated leptons are required to have $p_T > 10$ GeV. Events are selected which have a scalar-summed visible transverse momentum of $H_T>1$ TeV, and which have at least one $b$-jet inside one fat jet, at least one $b$-jet and two light jets inside the other fat jet, and at least one isolated lepton.

The observables that 