Energy scale and resolution for anti-$k_t$ jets with radius parameters $R=0.2$ and 0.6 measured in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

Abstract

Jets with different radius parameters $R$ are an important tool to probe quantum chromodynamics processes at different angular scales. Jets with small $R=0.2$ are instrumental in measurements of the substructure of large-$R$ jets resulting from collimated hadronic decays of energetic $W$, $Z$, and Higgs bosons, top quarks, and of potential new resonances. Measurements are presented of the energy scale and resolution of jets with radius parameters $R=0.2$ and 0.6 obtained with the ATLAS detector using $37 \text{fb}^{-1}$ of proton--proton collisions from the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=13$ TeV, with their associated uncertainties. A new in situ method to measure jet energy scale differences between data and Monte Carlo simulations is presented. The systematic uncertainties in the jet energy scale for central jets ($|\eta| < 1.2$) typically vary from 1% to about 5% as a function of $|\eta|$ at very low transverse momentum, $p_{\text{T}}$, of around 20 GeV for both $R=0.2$ and 0.6 jets. The relative energy resolution ranges from $(35 \pm 6)$% at $p_{\text{T}} = 20$ GeV to $(6 \pm 0.5)$% at $p_{\text{T}} = 300$ GeV for central $R=0.2$ jets, and is found to be slightly worse for $R=0.6$ jets. Finally, the effect of close-by hadronic activity on the jet energy scale is investigated and is found to be well modelled by the ATLAS Monte Carlo simulations.