Simulating W/Z+jets production at the Tevatron

TL;DR

The paper validates SHERPA's merging of tree-level matrix elements with parton showers for W/Z+jets production at the Tevatron, showing that the ME-PS merging yields reliable predictions at both parton and hadron levels when compared with other MCs and with data. By detailing the merging algorithm, scale choices, and the highest-multiplicity treatment, the authors demonstrate that Sudakov reweighting and k_perp-based separation produce accurate jet spectra and smooth transitions across jet multiplicities. The study finds good agreement with NLO results (via MCFM) for exclusive and inclusive jet observables and highlights SHERPA's effectiveness in modeling exclusive multi-jet final states, while identifying the remaining theoretical uncertainties in scale choices and low-p_T regions. Overall, SHERPA provides a robust framework for simulating W/Z+jets at hadron colliders, with strong potential for background modeling in complex final states.

Abstract

The merging procedure of tree-level matrix elements and the subsequent parton shower as implemented in the new event generator SHERPA will be validated for the example of W/Z+jets production at the Tevatron. Comparisons with results obtained from other approaches and programs and with experimental results clearly show that the merging procedure yields relevant and correct results at both the hadron and parton levels.

Figures (19)

• Figure 1: Two possible cluster configurations of a W+1 jet event. The dashed line highlights the hard $2 \to 2$ process.
• Figure 2: Three possible cluster configurations of a W+2 jet event. The dashed line highlights the hard $2 \to 2$ process, being either of Drell--Yan type (a), a vector boson production (b) or a pure QCD process (c).
• Figure 3: $p_\perp(W^-)$ and $p_\perp(e^-)$ for $Q_{\rm cut}=10$ GeV, $30$ GeV and $50$ GeV in comparison with $Q_{\rm cut}=20$ GeV.
• Figure 4: $\eta(W^-)$ and $\eta(e^-)$ for $Q_{\rm cut}=10$ GeV, $30$ GeV and $50$ GeV in comparison with $Q_{\rm cut}=20$ GeV.
• Figure 5: Differential jet rates for the $1 \to 0$, $2 \to 1$ and $3 \to 2$ transition (top to bottom), for $Q_{\rm cut}=10$ GeV, $30$ GeV, and $50$ GeV (from left to right). In each plot, the results are compared with those for $Q_{\rm cut}=20$ GeV.