- The paper presents the inaugural measurement of inclusive jet and dijet cross sections in 7 TeV proton-proton collisions, offering critical data to test QCD predictions.
- It utilizes the anti-kt algorithm with resolution parameters R = 0.4 and R = 0.6 to accurately quantify jet energy scale uncertainties and systematic effects.
- The findings demonstrate that NLO QCD calculations, adjusted with non-perturbative corrections, align with the experimental data, establishing a benchmark for future high-energy physics studies.
Measurement of Inclusive Jet and Dijet Cross Sections in Proton-Proton Collisions at 7 TeV with the ATLAS Detector
This paper, authored by the ATLAS Collaboration, presents the inaugural measurement of jet cross sections in proton-proton (pp) collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider (LHC). By utilizing an integrated luminosity of 17 nb−1 collected during the early data-taking phase, the paper aims to probe high transverse-momentum (pT) processes and evaluate quantum chromodynamics (QCD) predictions in a novel energy regime.
Methodology
The paper employs the anti-kt (AKT) algorithm for jet identification, using resolution parameters R = 0.4 and R = 0.6, to discern the impact of various soft QCD corrections. The paper reports systematic uncertainties predominantly originating from the jet energy scale (JES), which is confirmed to be within 7% for central jets exceeding 60 GeV in transverse momentum. The cross sections are evaluated as functions of jet transverse momentum and rapidity for single jets; corresponding distributions for dijet cross sections are presented in terms of dijet mass and the angular variable χ.
Results and Interpretation
The results are compared against next-to-leading-order (NLO) QCD calculations, which incorporate non-perturbative corrections derived from parton-shower MC generators and exhibit congruence with the measured data. This alignment supports the robustness of perturbative QCD in an unprecedented kinematic domain. Notably, the paper reveals that the theory underestimates the absolute cross sections, prompting further investigation into potential factors, such as the jet energy scale and PDF uncertainties, impacting the precision of these measurements.
Implications and Future Directions
The successful validation of NLO QCD predictions at such high energies provides a cornerstone for exploring TeV-scale physics and the intricate dynamics of QCD. This research enriches our understanding of the proton structure and enhances our capability to detect potential deviations indicative of new physics beyond the Standard Model.
Given the rapid data accumulation at LHC post the initial 17 nb−1, future studies will likely explore higher pT domains and reduce uncertainties, particularly those arising from luminosity and JES. These advancements will facilitate not only a deeper exploration of QCD but also a fortified search for new particles and interactions in the LHC's subsequent data eras.
Conclusion
This definitive measurement of inclusive jet and dijet cross sections at 7 TeV sets a benchmark for future experimental and theoretical studies. The results affirm the predictive capacity of NLO QCD and underscore the ATLAS detector's role as a pivotal instrument for high-energy physics investigations. As the LHC operation persists, continuous refinements in experimental measurements and theoretical models will propel exploration into uncharted territories of particle physics.