Energy scale and resolution for anti-kt jets with radius parameters R = SQUARE ROOT 0.2 and 0.6 measured in proton-proton collisions at SQUARE ROOTs = 13 TeV with the ATLAS detector

Abstract

Jets with different radius parameters R are an important tool for probing quantum chromodynamics processesat different angular scales. Jetswith small R = 0.2 areinstrumental in measurements of the substructure of large-R jets resulting from collimated hadronic decays of energeticW, Z, and Higgs bosons, top quarks, and of potentialnew resonances. This paper presents measurements of theenergy scale, resolution, and associated uncertainties of jetswith radius parameters R = 0.2 and 0.6, obtained using theATLAS detector. The results are based on 37 fb-1 of proton-proton collision data from the Large Hadron Collider at acentre-of-mass energy ofSQUARE ROOTs = 13TeV.Anewin situ methodfor measuring jet energy scale differences between data andMonte Carlo simulations is presented. The systematic uncertaintiesin the jet energy scale for central jets (|η| < 1.2)typically vary from 1% to about 5% as a function of |η| atvery low transverse momentum, pT, of around 20 GeV forboth R = 0.2 and 0.6 jets. The relative energy resolutionranges from (35 +- 6)% at pT = 20 GeV to (6 +- 0.5)% atpT = 300 GeV for central R = 0.2 jets, and is found to beslightly worse for R = 0.6 jets. Finally, the effect of close-byhadronic activity on the jet energy scale is investigated andis found to be well modelled by the ATLAS Monte Carlo simulations.