Measurement of inclusive jet and dijet cross-sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

TL;DR

This ATLAS study provides precise measurements of inclusive-jet and dijet cross-sections at 13 TeV using 3.2 fb$^{-1}$, leveraging a comprehensive jet-energy calibration and unfolding framework. The results are confronted with NLO and NNLO pQCD predictions, incorporating non-perturbative and electroweak corrections across multiple PDFs, revealing fair agreement in individual bins but notable tensions in a global fit; NNLO with a jet-based scale generally improves the description. The work demonstrates the sensitivity of high-$p_T$ jets and large-$M_{jj}$ spectra to PDFs and QCD dynamics, offering important input for PDF fits and precision tests of the Standard Model at the LHC.

Abstract

Inclusive jet and dijet cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb$^{-1}$ recorded in 2015 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-${k_t}$ algorithm with a radius parameter value of $R=0.4$. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to $|y|=3$. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within $|y|<3$, $y*$, up to $y*=3$. Next-to-leading-order, and next-to-next-to-leading-order for the inclusive jet measurement, perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.

Figures (12)

• Figure 1: Relative systematic uncertainty for the inclusive jet cross-section as a function of the jet for the first and last rapidity bins ((a) and (b) respectively) and for the dijet cross-section as a function of $\twomass{j}{j}$ for the first and last $y^{\mathrm{*}}$ bins ((c) and (d) respectively). The individual uncertainties are shown in different colours: the jet energy scale, jet energy resolution and the other uncertainties (jet cleaning, luminosity and unfolding bias). The total systematic uncertainty, calculated by adding the individual uncertainties in quadrature, is shown as a green line. The statistical uncertainty is shown as vertical black lines.
• Figure 2: Relative NLO QCD uncertainties in the jet cross-sections calculated using the CT14 PDF set. Panels a,b (c,d) correspond respectively to the first and last $|y|$ ($y^{\mathrm{*}}$) bins for the inclusive jet (dijet) measurement. The uncertainties due to the renormalisation and factorisation scale, the $\alpha_\text{s}$, the PDF and the total uncertainty are shown. The total uncertainty, calculated by adding the individual uncertainties in quadrature, is shown as a black line.
• Figure 3: Non-perturbative correction factors for the (inclusive jet, dijet) NLO pQCD prediction as a function of (jet , $\twomass{j}{j}$) for ((a),(c)) the first (rapidity, $y^{\mathrm{*}}$) bin and for ((b),(d)) the last (rapidity, $y^{\mathrm{*}}$) bin. The corrections are derived using Pythia 8 with the A14 tune with the NNPDF2.3 LO PDF set. The envelope of all MC configuration variations is shown as a band.
• Figure 4: Electroweak correction factors for the inclusive jet (dijet) cross-section as a function of the jet $p_{\mathrm{T}}$ ($\twomass{j}{j}$) for all $|y|$ ($y^{\mathrm{*}}$) bins.
• Figure 5: Inclusive jet cross-section s as a function of and $|y|$, for jets with $R=0.4$. The statistical uncertainties are smaller than the size of the symbols used to plot the cross-section values. The dark gray shaded areas indicate the experimental systematic uncertainties. The data are compared to NLO pQCD predictions calculated using NLOJET++ with $p_{\rm T}^{\mathrm{max}}$ as the QCD scale and the CT14 NLO PDF set, to which non-perturbative and electroweak corrections are applied. The light gray (yellow in the online version) shaded areas indicate the predictions with their uncertainties. At low and intermediate bins the experimental systematic uncertainties are comparable to the theory uncertainties (drawn on top) and therefore are barely visible.