Determination of jet calibration and energy resolution in proton-proton collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector

TL;DR

This paper details the precise calibration and energy resolution measurements of jets in proton-proton collisions at 8 TeV using the ATLAS detector, employing multiple in situ techniques for accuracy.

Contribution

It introduces a comprehensive jet calibration scheme with improved precision and detailed energy resolution measurements across a wide range of jet transverse momenta.

Findings

Calibration precision better than 1% for jets with 150 GeV < pT < 1500 GeV

Energy resolution of (8.4±0.6)% at 100 GeV pT

Energy resolution of (23±2)% at 20 GeV pT

Abstract

The jet energy scale, jet energy resolution, and their systematic uncertainties are measured for jets reconstructed with the ATLAS detector in 2012 using proton-proton data produced at a centre-of-mass energy of 8 TeV with an integrated luminosity of 20 fb$^{-1}$. Jets are reconstructed from clusters of energy depositions in the ATLAS calorimeters using the anti-$k_t$ algorithm. A jet calibration scheme is applied in multiple steps, each addressing specific effects including mitigation of contributions from additional proton-proton collisions, loss of energy in dead material, calorimeter non-compensation, angular biases and other global jet effects. The final calibration step uses several \textit{in situ} techniques and corrects for residual effects not captured by the initial calibration. These analyses measure both the jet energy scale and resolution by exploiting the transverse momentum balance in $\gamma$+jet, $Z$+jet, dijet, and multijet events. A statistical combination of these measurements is performed. In the central detector region, the derived calibration has a precision better than 1% for jets with transverse momentum 150 GeV $< p_{\mathrm{T}}<$ 1500 GeV, and the relative energy resolution is $(8.4\pm 0.6)$% for $p_{\mathrm{T}}=$ 100 GeV and $(23\pm 2)$% for $p_{\mathrm{T}}=$ 20 GeV. The calibration scheme for jets with radius parameter $R=1.0$, for which jets receive a dedicated calibration of the jet mass, is also discussed.