Measurement of the Inclusive Production Cross Sections for Forward Jets and for Dijet Events with One Forward and One Central Jet in pp Collisions at
7 TeV
Abstract
The inclusive production cross sections for forward jets, as well for jets in dijet events with at least one jet emitted at central and the other at forward pseudorapidities, are measured in the range of transverse momenta
GeV/c in proton-proton collisions at

= 7
TeV by the CMS experiment at the LHC. Forward jets are measured within pseudorapidities

, and central jets within the

range. The differential cross sections

are compared to predictions from three approaches in perturbative quantum chromodynamics: (i) next- to-leading-order calculations obtained with and without matching to parton-shower Monte Carlo simulations, (ii) PYTHIA and HERWIG parton-shower event generators with different tunes of parameters, and (iii) CASCADE and HEJ models, including different non-collinear corrections to standard single-parton radiation. The single-jet inclusive forward jet spectrum is well described by all models, but not all predictions are consistent with the spectra observed for the forward-central dijet events.
Paper Plots from FWD-11-002 (click on plot to get .pdf)
Figure |
Caption |
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Measured differential cross sections for jets as a function of , before unfolding the energy resolution (black dots), compared to detector-level MC simulations generated with PYTHIA and HERWIG (histograms) for inclusive forward jets. |
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Measured differential cross sections for jets as a function of , before unfolding the energy resolution (black dots), compared to detector-level MC simulations generated with 3 different versions of PYTHIA and HERWIG (histograms) for central jets in dijet events. |
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Measured differential cross sections for jets as a function of , before unfolding the energy resolution (black dots), compared to detector-level MC simulations generated with 3 different versions of PYTHIA and HERWIG (histograms) for forward jets in dijet events. |
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The bin-by-bin unfolding correction factors as a function of for inclusive forward jets. Panel shows the individual correction factors obtained with PYTHIA 6 and HERWIG 6. The hatched band represents the uncertainties assigned to the correction factors. |
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The bin-by-bin unfolding correction factors as a function of for central jets in dijet events. Figure shows the average values obtained for the two MC generators (black histograms).The hatched band represents the uncertainties assigned to the correction factors. |
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The bin-by-bin unfolding correction factors as a function of for forward jets in dijet events. Figure shows the average values obtained for the two MC generators (black histograms).The hatched band represents the uncertainties assigned to the correction factors. |
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Systematic uncertainties as a function of jet for inclusive forward production. The outer limits of the grey areas show the overall uncertainties, from adding in quadrature uncertainties from the JES, the unfolding and the luminosity. |
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Systematic uncertainties as a function of jet for central jet spectra in dijet events. The outer limits of the grey areas show the overall uncertainties, from adding in quadrature uncertainties from the JES, the unfolding and the luminosity. |
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Systematic uncertainties as a function of jet for central jet spectra in dijet events. The outer limits of the grey areas show the overall uncertainties, from adding in quadrature uncertainties from the JES, the unfolding and the luminosity. |
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Uncertainties on the predicted NLO inclusive forward jet spectrum. Plot shows the contributions from non-perturbative effects, choice of PDF and the value of the strong cou- pling αS (computed with the PDF4LHC prescription), and uncertainties associated with the renormalization and fragmentation scales. |
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Uncertainties on the predicted NLO inclusive forward jet spectrum. Plot shows the uncertainties from NP, PDF and (obtained with HERAPDF1.0), and the theoretical scales. Total uncertainties are obtained by adding quadratically the uncertainties on NP, PDF and the scales. |
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Inclusive jet cross section at forward pseudorapidities fully corrected and unfolded, compared to particle-level predictions from PYTHIA 6, PYTHIA 8, HERWIG 6, NLOJET++ corrected for non-perturbative effects, POWHEG, CASCADE and HEJ. |
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Ratio of theory/data for the forward jet spectrum. The dark band shows the theoretical uncertainty on the NLO predictions. |
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Ratio of the inclusive forward jet spectrum for data over the NLO predictions using the CT10 PDF, as a function of , shown with the statistical (error bars) as well as systematic uncertainties (grey band). Additional predictions are shown for all the central PDF prdictions (curves).The corresponding PDF uncertainties are shown as coloured bands around the ratios. |
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Additional predictions are shown for for the MSTW2008 and NNPDF2.1 sets. Common theoretical uncertainties from choices of scale and non-perturbative corrections are indicated by dashed (magenta) curves. |
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Additional predictions are shown for the HERAPDF1.0 and ABKM09 PDF. Common theoretical uncertainties from choices of scale and non-perturbative corrections are indicated by dashed (magenta) curves. |
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Differential cross sections as a function of jet for dijet events with at least one central jet and one forward jet, compared to predictions from several models. The error bars on all data points (which are smaller than the size of the markers) reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Differential cross sections as a function of jet for dijet events with at least one central jet and one forward jet, compared to predictions from several models. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Differential cross sections as a function of jet for dijet events with at least one central jet and one forward jet, compared to predictions from several models. The error bars on all data points (which are smaller than the size of the markers) reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Differential cross sections as a function of jet for dijet events with at least one central jet and one forward jet, compared to predictions from several models. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Ratio of theory to data for differential cross sections as a function of , for central jets produced in dijet events. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Ratio of theory to data for differential cross sections as a function of , for forward jets produced in dijet events. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Ratio of theory to data for differential cross sections as a function of , for central jets produced in dijet events. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
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Ratio of theory to data for differential cross sections as a function of , for forward jets produced in dijet events. The error bars on all data points reflect just statistical uncertainties, with systematic uncertainties plotted as grey bands. |
Paper Table
Measured

-dependent differential cross sections for inclusive forward jets (second column), and for central (third column) and forward (last column) jets in dijet events. The first (second) uncertainty reflects the statistical (systematic) contribution.
Links
Submitted to the J. High Energy Phys.
arXiv:1202.0704
;
CDS