Search for pair production of scalar leptoquarks decaying to first or second generation leptons and boosted hadronically decaying top quarks in $pp$ collisions at $\sqrt{s}=13 \ \mathrm{TeV}$ with the ATLAS detector

A search for pair production of scalar leptoquarks, each decaying to a top quark and either an electron or a muon, is presented. This is the first leptoquark search using ATLAS data to investigate top-philic cross-generational couplings that could provide attractive explanations for recently observed anomalies. This analysis targets heavy leptoquarks in which the top quarks each decay within a single high $p_{\mathrm{T}}$ large radius jet. The full Run 2 dataset is exploited, consisting of 139 fb$^{-1}$ of data collected from $pp$ collisions at $\sqrt{s}=13 \ \mathrm{TeV}$ from 2015 to 2018 with the ATLAS detector at the CERN Large Hadron Collider. In the absence of any significant deviation from the background expectation, lower limits on the leptoquark masses are set at 1480 GeV and 1470 GeV for the electron and muon channels, respectively.