Jet energy scale measurements and their systematic uncertainties in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector (1703.09665v2)

Abstract: Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of $\sqrt{s} = 13$ TeV, corresponding to an integrated luminosity of 3.2 fb$^{-1}$ collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-$k_{t}$ algorithm with radius parameter $R = 0.4$. Jets are calibrated with a series of simulation-based corrections and in situ techniques. In situ techniques exploit the transverse momentum balance between a jet and a reference object such as a photon, $Z$ boson, or multijet system for jets with $20 < p_{T} < 2000$ GeV and pseudorapidities of $|\eta|<4.5$, using both data and simulation. An uncertainty in the jet energy scale of less than 1% is found in the central calorimeter region ($|\eta| < 1.2$) for jets with $100 < p_{T} < 500$ GeV. An uncertainty of about 4.5% is found for low-$p_{T}$ jets with $p_{T} = 20$ GeV in the central region, dominated by uncertainties in the corrections for multiple proton-proton interactions. The calibration of forward jets ($|\eta| > 0.8$) is derived from dijet $p_{T}$ balance measurements. For jets of $p_{T} = 80$ GeV, the additional uncertainty for the forward jet calibration reaches its largest value of about 2% in the range $|\eta| > 3.5$ and in a narrow slice of $2.2 < |\eta| < 2.4$.

• The paper presents precise JES calibration in proton-proton collisions using simulation corrections and in situ momentum balance methods.
• It achieves sub-1% systematic uncertainty for central jets between 100 and 500 GeV while noting larger uncertainties for low-pT and forward jets.
• The improved calibration advances reliable Standard Model measurements and new physics searches, guiding future high-energy experiments.

Jet Energy Scale Measurements in Proton-Proton Collisions at the ATLAS Detector

This paper, presented by the ATLAS Collaboration, details the precision measurements of the Jet Energy Scale (JES) within the ATLAS detector at CERN's Large Hadron Collider (LHC). The paper provides a meticulous calibration of the JES using data collected from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 3.2 fb$^{-1}$.

Calibration Procedure and Techniques

Jets are reconstructed using energy deposits in calorimeters, employing the anti-$k_t$ algorithm with a radius parameter $R = 0.4$. The calibration process involves simulation-based corrections and \emph{in situ} techniques. Notably, the \emph{in situ} methods utilize the momentum balance between a jet and a reference object such as a photon, Z boson, or a multijet system. This methodology spans a wide kinematic range for transverse momentum ($p_T$): from 20 GeV to 2000 GeV, and pseudorapidities of $|\eta| < 4.5$.

Systematic Uncertainties and JES Precision

The results indicate an impressive precision, with a systematic uncertainty in the JES below 1% for jets in the central calorimeter region ($|\eta| < 1.2$) with $100 < p_T < 500$ GeV. Conversely, a higher uncertainty of about 4.5% is reported for low-$p_T$ jets ($p_T = 20$ GeV) in the same region, primarily due to multiple proton-proton interaction corrections. The calibration for forward jets ($|\eta| > 0.8$) derives from dijet $p_T$ balance measurements, with an additional uncertainty peaking at 2% for $p_T = 80$ GeV in the most forward regions ($|\eta| > 3.5$) and near $|\eta| \approx 2.3$.

Implications and Future Directions

This comprehensive calibration effort enhances the accuracy of jet measurements, which are crucial for both standard model measurements and searches for new physics phenomena. As the LHC continues to deliver higher luminosities and energies, the methodologies refined in this paper will be vital for maintaining data fidelity. Further work may consider augmenting these methods with advanced machine learning techniques to handle even larger datasets and more complex physics scenarios.

The indirect insights gained from this calibration extend beyond jet physics, potentially influencing detector calibration strategies and methodologies in high-energy physics experiments globally. Future advancements may leverage improvements in simulation fidelity and real-time data processing capabilities, driven by developments in computational technologies. Thus, continued collaboration and technological cross-pollination will be essential to harness the full scientific potential of upcoming LHC phases.