StandardModelCSCResultsWZJets
Introduction
This page provides information and plots for W/Z+jets studies from ATLAS CSC book, as
published in
ATLAS Collaboration, Expected Performance of the ATLAS Experiment, Detector, Trigger and Physics, Geneva 2008. CERN-OPEN-2008-020, ISBN978-92-9083-321-5, arXiv:0901.0512v1 [hep-ex].
Production of Jets in Association with Z Bosons
Abstract
We simulate a measurement of the inclusive Z(->e+e-/m+m-) + jets cross-section with the ATLAS experiment in pp collisions at 14
TeV for an integrated luminosity of 1 fb-1 using fully-simulated signal and background Monte Carlo data sets. The reconstruction of leptons and of missing transverse energy becomes more complex in the presence of a multi-jet final state. We quantify the reconstruction differences with respect to those observed for inclusive Z production. We derive statistical and systematic limitations in terms of probing the perturbative QCD predictions and discriminating between predictions of different event generators.
Measurement of Z + jets Cross-Sections
Caption Figure 2: Comparison of the distribution of the pT of the leading jet (a) and the next-to-leading jet (b) for the generated (hadron-level) Monte Carlo and for the reconstructed quantities without any correction, after the corrections for electron triggering and reconstruction and after applying in addition the jet-releated corrections.
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Caption Figure 4: The inclusive jet cross-section (a) and the distribution of the pT of the leading jet (b), as predicted by NLO (LO) MCFM (corrected to the hadron-level) and by ALPGEN for the Z -> e+e- +jets process.
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Caption Figure 5: Uncertainty on the ratio of measurement and theory for the inclusive jet cross-section (a) and the pT of the leading jet (b) for the Z -> e+e- +jets process.
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Results Tables
Process |
σ (fb) |
frac(%) |
σ (fb) |
frac(%) |
σ (fb) |
frac(%) |
|
Z->ll+ >=1 jet |
Z->ll+ >=2 jet |
Z->ll+ >=3 jet |
Z->e+e- + jets analysis |
Z->e+e- |
23520±145 |
91.9±0.8 |
4894±45 |
87.9±1.3 |
900±15 |
80.0±2.4 |
QCD jets |
1545±89 |
6.0±0.4 |
336±42 |
6.0±0.8 |
78±20 |
6.9±1.8 |
ttbar |
496±28 |
1.9±0.1 |
333±23 |
6.0±0.4 |
146±15 |
13.0±1.4 |
W->eν |
(28±13) |
(0.1±0.05) |
(5.9±2.6) |
(0.1±0.05) |
(1.1±0.5) |
(0.1±0.05) |
Z->ττ |
3.2±1.2 |
0.01±0.01 |
(0.67±0.25) |
(0.01±0.01) |
(0.1±0.05) |
(0.01±0.01) |
Z->μ+μ- + jets analysis |
Z->μ+μ- |
59400±650 |
96.2±1.0 |
12600±300 |
90.1±1.9 |
2450±100 |
89.7±3.7 |
QCD (bbar) |
1230±550 |
2.0±0.9 |
600±300 |
4.3±2.2 |
0±110 |
0.0±4.0 |
ttbar |
1140±110 |
1.8±1.8 |
790±90 |
5.7±0.2 |
275±50 |
10.2±1.9 |
W->μν |
0±180 |
0.0±0.3 |
0±30 |
0.0±0.2 |
0±5 |
0.0±0.2 |
Caption Table 1: The accepted cross-sections (σ , in fb) and the corresponding fraction of the total sample
(in %) for signal and for the background channels in the Z->e+e- +jets and the Z->μ+μ- +jets
analyses, after applying the cuts outlined in Section 3. The numbers in brackets are extrapolated from
results obtained for a lower jet multiplicity. Errors shown are statistical only.
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Major updates:
--
StefanTapprogge - 5 Dec 2008
--
AlessandroTricoli - 12 Jan 2009
Responsible:
AlessandroTricoli
Last reviewed by:
--
AlessandroTricoli - 12 Jan 2009