Present Limits on the Precision of SM Predictions for Jet Energies

TL;DR

This paper assesses the theoretical uncertainties affecting the precision of jet energy measurements in proton-antiproton collisions, highlighting the dominant role of parton showering uncertainties and proposing a method applicable to LHC data analysis.

Contribution

It introduces a method to evaluate the impact of various theoretical uncertainties on jet energy measurements using Z+jet events, applicable to current and future collider experiments.

Findings

Parton showering at large angles causes the largest uncertainty.

The method can be applied to LHC data to evaluate jet energy prediction uncertainties.

Distributions are suitable for comparison with modern event generators.

Abstract

We investigate the impact of theoretical uncertainties on the accuracy of measurements involving hadronic jets. The analysis is performed using events with a Z boson and a single jet observed in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV in 4.6 $\mathrm{fb^{-1}}$ of data from the Collider Detector at Fermilab (CDF). The transverse momenta (\pt) of the jet and the boson should balance each other due to momentum conservation in the plane transverse to the direction of the $p$ and $\bar{p}$ beams. We evaluate the dependence of the measured \pt-balance on theoretical uncertainties associated with initial and final state radiation, choice of renormalization and factorization scales, parton distribution functions, jet-parton matching, calculations of matrix elements, and parton showering. We find that the uncertainty caused by parton showering at large angles is the largest amongst the listed uncertainties. The proposed method can be re-applied at the LHC experiments to investigate and evaluate the uncertainties on the predicted jet energies. The distributions produced at the CDF environment are intended for comparison to those from modern event generators and new tunes of parton showering.