Physics potential for boosted topologies in top-quark pair production at a multi-TeV Compact Linear Collider

The physics potential for boosted topologies in top-quark pair production is studied at centre-of-mass energies of 1.4 TeV and 3 TeV at the proposed high-luminosity linear electron-positron Compact Linear Collider (CLIC). The analyses presented in this paper focus on "single lepton+jets" $t\overline{t}$ final states and apply jet sub-structure techniques to explore the highly collimated jet environment above 1 TeV. The charged lepton is used to determine the charge of both top quarks. We present results for the tt production cross section and the forward-backward asymmetry in the kinematic region $\sqrt{s^{'}}\geq 1.2$ TeV ($\sqrt{s^{'}}\geq 2.6$ TeV) for operation at 1.4 TeV (3 TeV), where $\sqrt{s^{'}}$ is the effective collision energy, taking into account the CLIC luminosity spectrum and initial-state radiation. The results are based on detailed Monte Carlo simulation studies with a GEANT4 based simulation of the CLIC_ILD detector concept and particle-flow based event reconstruction. All data samples considered include beam-induced backgrounds and other relevant background processes. The expected precision on the $t\overline{t}$ production cross section and the forward-backward asymmetry are 1.1% (2.0%) and 1.4% (2.3%), respectively, for operation at 1.4 TeV (3 TeV) with an integrated luminosity of 2.0ab$^{−1}$ (4.0ab$^{−1}$) and with $-$80% electron polarisation. For improved Beyond Standard Model reach, operation is also foreseen at $+$80% electron polarisation, with an integrated luminosity of 0.5 ab$^{−1}$ (1.0ab$^{−1}$) at 1.4 TeV (3 TeV), where the corresponding numbers are about a factor 2.5 higher.