Uncertainties in NLO + parton shower matched simulations of inclusive jet and dijet production

TL;DR

This paper assesses uncertainties in NLO + parton shower simulations of jet production at the LHC, highlighting dominant sources of error in different phase space regions and their impact on theoretical predictions.

Contribution

It provides a detailed quantification of uncertainties in MC@NLO matched simulations, focusing on the effects of parton shower parameters and underlying event modeling.

Findings

Uncertainty from parton shower parameters dominates in Sudakov-dominated regions.

Underlying event modeling introduces significant uncertainties in other regions.

Quantitative analysis of simulation uncertainties using early LHC data.

Abstract

We quantify uncertainties in the Monte-Carlo simulation of inclusive and dijet final states, which arise from using the MC@NLO technique for matching next-to-leading order parton level calculations and parton showers. We analyse a large variety of data from early measurements at the LHC. In regions of phase space where Sudakov logarithms dominate over high-energy effects, we observe that the main uncertainty can be ascribed to the free parameters of the parton shower. In complementary regions, the main uncertainty stems from the considerable freedom in the simulation of underlying events.