Reconstruction of vectorlike top partner from fully hadronic final states

We investigate the potential to search for the vectorlike top partner in fully hadronic final states at the LHC. An algorithm is developed that kinematically reconstructs the vectorlike top. We show that for moderate masses and a large branching fraction into the top quark and Higgs boson, the reconstruction works with good quality.

Figure 1

$H_T$ distribution for signal and background processes (detector level). The red (blue) line corresponds to signal events with $m_{t^{\prime }}=800$ (900) GeV and is 1000 times enlarged, and the black line describes the main backgrounds which contain $bb\overline{b}\overline{b}$, $t\overline{t}$, $t\overline{t}b\overline{b}$ and $t\overline{t}h$ processes.

Figure 2

Distribution of bottom quark isolation for signal events (parton level). The horizontal axis corresponds to the smallest distance between each (anti)bottom quark and any other particle in the partonic final state, $\mathrm{\Delta }{R}_{b_i}^{(\min )}=\underset{j\ne b_i}{\min }\mathrm{\Delta }R(b_i,j)$ ($i=1,\dots ,6$).

Figure 3

(left) The smallest distance between any two of the top quarks and Higgs bosons in $pp\to t^{\prime }\overline{t^{\prime }}\to th\overline{t}h$ (parton level). (right) Distribution of the number of reconstructed fat jets for the signal (detector level).

Figure 4

(upper) The mass distribution of reconstructed vectorlike tops (detector level). The red and blue lines correspond to the signal for different masses of the vectorlike top, $m_{t^{\prime }}=800\mathrm{GeV}$ and $m_{t^{\prime }}=900\mathrm{GeV}$, respectively. The black line shows the sum of all relevant background processes; their breakdown is given by the filled curves. Event numbers are stacked. (lower) The mass distribution for signal events only (detector level).