Jet reclustering and close-by effects in ATLAS run II

The reconstruction of hadronically-decaying, high-$p_{T}$ $W$, $Z$ and Higgs bosons and top quarks is instrumental to exploit the physics potential of the ATLAS detector in $pp$ collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider (LHC). The jet reclustering procedure reconstructs such objects by using calibrated anti-$k_{t}$ jets as inputs to the anti-$k_{t}$ algorithm with a larger distance parameter. The performance of these reclustered large-radius jets during LHC Run 2 is studied, and compared with that of trimmed anti-$k_{t}$ large-radius jets directly constructed from locally calibrated topological clusters. The propagation of calibrations to reclustered jets is found to be sufficient to restore their average energy and mass scales to particle level. The modelling of small-radius anti-$k_{t}$ jets in each other's vicinity is studied using methods which combine tracking and calorimeter information. Systematic uncertainties resulting from the propagation of the uncertainties on the input jets to the reclustering procedure are studied. Comparisons between 33.2 fb$^{-1}$ of data collected during 2016 operations and simulation are shown, and the relative jet mass scale and resolution for reclustered and conventional jets are extracted using the forward-folding technique.