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| CMS-PAS-FSQ-12-023 | ||
| Measurement of the very forward inclusive jet cross section in pp collisions at $\sqrt{s} =$ 7 TeV | ||
| CMS Collaboration | ||
| April 2016 | ||
| Abstract: The measurement of the very forward ($-6.6 \leq \eta \leq -5.2$) inclusive jet energy spectrum with the CASTOR calorimeter at CMS in pp collisions with $\sqrt{s} = $ 7 TeV is presented. A fully corrected energy spectrum is presented and compared to a set of Monte Carlo generated jet energy spectra. | ||
| Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Comparison of the measured detector level jet energy spectrum between data and three models, after calibration. |
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Figure 2-a:
The response matrix as determined for jets with $E > $ 150 GeV for PYTHIA-6 (Z2*). Negative values are indicated with black rectangles. |
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Figure 2-b:
The covariance matrix for the unfolded distribution after 30 iterations for PYTHIA-6 (Z2*). Negative values are indicated with black rectangles. |
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Figure 3-a:
The unfolded CASTOR jet energy spectrum: data has been unfolded with the D'Agostini iteration method with early stopping, using 30 iterations. The inner pink band represents 3.6% luminosity uncertainty; the grey band shows the systematic errors attributed to the luminosity, model and position dependence; the yellow band shows the total uncertainty including the energy scale uncertainty. Several PYTHIA tunes (bottom) and EPOS-LHC, QGSJETLL-4 and SIBYLL.1 (top) are compared to the unfolded distribution, and have been normalized to the total number of available data events. The jet energy threshold is $E = $150 GeV, the spectrum is plotted from $E = $ 300 GeV. |
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Figure 3-b:
The unfolded CASTOR jet energy spectrum: data has been unfolded with the D'Agostini iteration method with early stopping, using 30 iterations. The inner pink band represents 3.6% luminosity uncertainty; the grey band shows the systematic errors attributed to the luminosity, model and position dependence; the yellow band shows the total uncertainty including the energy scale uncertainty. Several PYTHIA tunes (bottom) and EPOS-LHC, QGSJETLL-4 and SIBYLL.1 (top) are compared to the unfolded distribution, and have been normalized to the total number of available data events. The jet energy threshold is $E = $150 GeV, the spectrum is plotted from $E = $ 300 GeV. |
| Tables | |
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Table 1:
Contributions to CASTOR energy scale uncertainty [21]. |
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Table 2:
Asymmetric systematic uncertainties for three values in the energy spectrum. The total uncertainty is the quadratic sum of the separate errors and a 3.6% luminosity uncertainty. |
| Summary |
| A measurement of the very forward inclusive jet cross section in proton-proton collisions with a center-of-mass energy of $\sqrt{s} = $ 7 TeV is presented, based on data taken by the CMS detector. The data are corrected for incomplete energy reconstruction and a method for correcting the obtained jet spectrum for effects as coinciding or partially contained jets is explained. Several sources of systematic uncertainty have been investigated and applied to the final energy spectrum. The current energy scale uncertainty of the CASTOR calorimeter does not allow for precise measurements of deviations between the data and theories. The data are compared with several models based on DGLAP + collinear factorization as well as models based on Reggeon theory. No significant deviations between data and theory are observed within systematic uncertainties. |
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Compact Muon Solenoid LHC, CERN |
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