Jet cross sections at the LHC and the quest for higher precision

TL;DR

This work delivers a comprehensive, high-precision QCD study of $H$+jet, $Z$+jet, and dijet production at the LHC across a wide range of jet radii $R$. By combining NNLOJET fixed-order predictions with NLO+PS results from Sherpa, Herwig, and POWHEG BOX, and by carefully analyzing jet shapes, $K$-factors, and scale and non-perturbative uncertainties, the authors quantify the impact of jet definition on theory predictions and experimental analyses. They show that NNLO reduces scale uncertainties substantially and that NLO+PS provides reliable resummation-consistent predictions, while identifying regimes (notably small-$R$) where special uncertainty treatments are required. The study provides practical guidance for precision phenomenology, PDF fits, and boosted-object measurements, with robust non-perturbative corrections and cross-generator consistency demonstrated. $H_T$- and $H_{T,j}$-based dynamical scales, antenna-subtraction techniques, and careful uncertainty prescriptions emerge as key tools for reliable LHC predictions in jet-rich final states.

Abstract

We perform a phenomenological study of $Z$ plus jet, Higgs plus jet and di-jet production at the Large Hadron Collider. We investigate in particular the dependence of the leading jet cross section on the jet radius as a function of the jet transverse momentum. Theoretical predictions are obtained using perturbative QCD calculations at the next-to and next-to-next-to-leading order, using a range of renormalization and factorization scales. The fixed order predictions are compared to results obtained from matching next-to-leading order calculations to parton showers. A study of the scale dependence as a function of the jet radius is used to provide a better estimate of the scale uncertainty for small jet sizes. The non-perturbative corrections as a function of jet radius are estimated from different generators.

Figures (19)

• Figure 1: Jet shapes for Higgs and $Z$ plus jets and inclusive jets
• Figure 2: $K$-factors for Higgs plus jets (top), $Z$ plus jets (middle) and inclusive jet production (bottom).
• Figure 3: The cross sections for $H +\ge1$ jet, $Z +\ge1$ jet, and dijet production from NNLOJET, as a function of the inclusive jet $p_T$ at LO, NLO and NNLO. To illustrate the spread induced on the cross section, representative values of $R\in[0.3,0.5,0.7,1.0]$ are shown.
• Figure 4: The scale variations at LO, NLO, and NNLO from NNLOJET for Higgs and $Z$ boson production, as a function of the boson transverse momentum, are shown. For comparison, the nominal NLO NLO+PS predictions are also shown. The generator predictions are scaled with the inclusive $K_{incl}$ factor with Higgs(Z) $p_\perp > 150$ GeV, see Fig. \ref{['fig:K-factors']}.
• Figure 5: The ratio between results computed in HEFT and the full Standard Model for the transverse momentum spectrum of the Higgs boson (left) and the leading jet (right) in Higgs plus jet events. Results labeled NLO' are derived using the approximation of Buschmann:2014sia.