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| CMS-PAS-SMP-16-014 | ||
| Measurements of inclusive 2-jet, 3-jet and 4-jet azimuthal correlations in pp collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| March 2017 | ||
| Abstract: Measurements of the correlation of azimuthal angles between the two jets with the largest transverse momenta ($p_\mathrm{T}$) in inclusive 2-jet, 3-jet, and 4-jet topologies are presented for several regions of the leading jet transverse momentum up to 4 TeV. For the case of 3-jet and 4-jet topologies measurements of the correlation of minimum azimuthal angles between any two of the three or four leading $p_\mathrm{T}$ jets are also presented. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The results are generally well reproduced by predictions using Monte Carlo event generators which combine perturbative QCD calculations up to next-to-leading-order accuracy with contributions from parton showers, hadronization, and multiparton interactions. The features of the different models considered in the comparisons and their performance on describing the measurement are discussed. | ||
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inSPIRE record ;
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These preliminary results are superseded in this paper, EPJC 78 (2018) 566. The superseded preliminary plots can be found here. |
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| Figures & Tables | Summary | Additional Figures | References | CMS Publications |
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| Figures | |
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Figure 1:
Normalized inclusive 2-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ for nine $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions, scaled by multiplicative factors for presentation purposes. The error bars on the data points include statistical and systematic uncertainties. Overlaid on the data are predictions from the ph-2j+pythia8 event generator. |
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Figure 2:
Ratios of pythia8 , herwig++ , and MadGraph+pythia8 predictions to the normalized inclusive 2-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 3:
Ratios of ph-2j+pythia8 , ph-2j+herwig++ , ph-3j+pythia8 , and herwig7 predictions to the normalized inclusive 2-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 4:
Normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ for eight $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions, scaled by multiplicative factors for presentation purposes. The error bars on the data points include statistical and systematic uncertainties. Overlaid on the data are predictions from the ph-2j+pythia8 event generator. |
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Figure 5:
Ratios of pythia8 , herwig++ , and MadGraph+pythia8 predictions to the normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 6:
Ratios of ph-2j+pythia8 , ph-2j+herwig++ , ph-3j+pythia8 , and herwig7 predictions to the normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 7:
Normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ for eight $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions, scaled by multiplicative factors for presentation purposes. The error bars on the data points include statistical and systematic uncertainties. Overlaid on the data are predictions from the ph-2j+pythia8 event generator. |
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Figure 8:
Ratios of pythia8 , herwig++ , and MadGraph+pythia8 predictions to the normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 9:
Ratios of ph-2j+pythia8 , ph-2j+herwig++ , ph-3j+pythia8 , and herwig7 predictions to the normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {1,2}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 10:
Normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ for eight $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions, scaled by multiplicative factors for presentation purposes. The error bars on the data points include statistical and systematic uncertainties. Overlaid on the data are predictions from the ph-2j+pythia8 event generator. |
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Figure 11:
Ratios of pythia8 , herwig++ , and MadGraph+pythia8 predictions to the normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
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Figure 12:
Ratios of ph-2j+pythia8 , ph-2j+herwig++ , ph-3j+pythia8 , and herwig7 predictions to the normalized inclusive 3-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
png pdf |
Figure 13:
Normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ for eight $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions, scaled by multiplicative factors for presentation purposes. The error bars on the data points include statistical and systematic uncertainties. Overlaid on the data are predictions from the ph-2j+pythia8 event generator. |
png pdf |
Figure 14:
Ratios of pythia8 , herwig++ , and MadGraph+pythia8 predictions to the normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
png pdf |
Figure 15:
Ratios of ph-2j+pythia8 , ph-2j+herwig++ , ph-3j+pythia8 , and herwig7 predictions to the normalized inclusive 4-jet cross section differential in $ {\Delta \phi _\text {2j}^\text {min}} $ , for all $ { {p_{\mathrm {T}}} ^{\text {max}}} $ regions. The solid band indicates the total experimental uncertainty and the error bars on the MC points represent the statistical uncertainties of the simulated data. |
| Tables | |
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Table 1:
The integrated luminosity for each trigger sample considered in this analysis. |
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Table 2:
Monte Carlo event generators used for comparison in this analysis. Version of the generators, PDF set, underlying event tune, and corresponding references are listed. |
| Summary |
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Measurements of the normalized inclusive 2-jet, 3-jet, and 4-jet cross sections differential in $ {\Delta \phi _\text {1,2}} $ and of the normalized inclusive 3-jet, and 4-jet cross sections differential in $ {\Delta \phi _\text {2j}^\text {min}} $, are presented for several regions in the leading-jet transverse momentum $ p_{\mathrm{T}}^{\text{max}} $. The measurements are performed using data collected during 2016 with the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$ of proton-proton collisions at $ \sqrt{s} = $ 13 TeV. The measured distributions in $ {\Delta \phi _\text {1,2}} $ and $ {\Delta \phi _\text {2j}^\text {min}} $ are compared to predictions from PYTHIAE, HERWIGpp, MadGraph + PYTHIAE, POWHEGTWOJET matched to PYTHIAE and HERWIGpp, POWHEGTHREEJET + PYTHIAE, and HERWIGSEVEN event generators. The LO PYTHIAE dijet event generator exhibits small deviations from the $ {\Delta \phi _\text {1,2}} $ measurements, and fails to describe the $ {\Delta \phi _\text {2j}^\text {min}} $ distributions. The HERWIGpp event generator exhibits the largest deviations from the $ {\Delta \phi _\text {1,2}} $ measurements but provides a reasonable description of the $ {\Delta \phi _\text {2j}^\text {min}} $ distributions. The tree-level multijet event generator MadGraph in combination with PYTHIAE for showering, hadronization, and multiparton interactions provides a good overall description of the measurements except for the $ {\Delta \phi _\text {2j}^\text {min}} $ distributions in the 4-jet case where the generator seems to reach its limit. The dijet NLO POWHEGTWOJET event generator exhibits deviations from the $ {\Delta \phi _\text {1,2}} $ measurements, but provides a good description of the $ {\Delta \phi _\text {2j}^\text {min}} $ observable. The three jet NLO POWHEGTHREEJET event generator exhibits large deviations from the measurements and describe the considered multijet observables in a less accurate way than the predictions generated by POWHEGTWOJET. Parton-shower contributions are responsible for the different behaviour of the POWHEGTWOJET and POWHEGTHREEJET predictions. Finally, predictions from the dijet NLO HERWIGSEVEN event generator provide a very good description of the $ {\Delta \phi _\text {1,2}} $ measurements, showing a very large improvement in comparison to HERWIGpp. All these observations emphasize the need to improve predictions for multijet production. Similar observations, for the inclusive 2-jet cross sections differential in $ {\Delta \phi _\text {1,2}} $, were reported previously by CMS [5] at a different center-of-mass energy. The extension of $ {\Delta \phi _\text {1,2}} $ correlations, and the measurement of the $ {\Delta \phi _\text {2j}^\text {min}} $ distributions in inclusive 3-jet and 4-jet topologies are new results of the present analysis. |
| Additional Figures | |
png pdf |
Additional Figure 1:
A three jets event display. Leading jet $ {p_{\mathrm {T}}} =$ 709.026 GeV, $y=-0.396$, $\phi = 1.544 $ rad. Second jet $ {p_{\mathrm {T}}} =$ 708.860 GeV, $y= 0.343$, $\phi =-2.655 $ rad. Third jet $ {p_{\mathrm {T}}} =$ 702.888 GeV, $y= 0.304$, $\phi =-0.561 $ rad. |
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Additional Figure 2:
A four jets event display. Leading jet $ {p_{\mathrm {T}}} = $ 234.481 GeV, $y=-0.714$, $\phi =-2.820 $ rad. Second jet $ {p_{\mathrm {T}}} =$ 223.978 GeV, $y= 1.477$, $\phi = 0.349 $ rad. Third jet $ {p_{\mathrm {T}}} =$ 216.236 GeV, $y= 0.375$, $\phi = 1.977 $ rad. Fourth jet $ {p_{\mathrm {T}}} =$ 195.639 GeV, $y=-0.823$, $\phi =-1.199 $ rad. |
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