CMS-PAS-SMP-16-003 | ||

Measurement of the differential cross section for inclusive isolated photon and photon+jets production in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||

CMS Collaboration | ||

June 2018 | ||

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Abstract:
Measurements of inclusive isolated photon and photon+jets production in proton-proton collisions at $\sqrt{s} = $ 13 TeV are presented. The analysis uses data collected by the CMS experiment in 2015, corresponding to an integrated luminosity of 2.26 fb$^{-1}$. The cross section for inclusive isolated photon production is measured as a function of the photon transverse momentum and rapidity. The cross section for photon+jets production is measured as a function of the photon transverse momentum, the photon rapidity, and the rapidity of the jet with the highest transverse momentum. The experimental measurements are found to be in agreement with recent theoretical predictions.
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Links:
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These preliminary results are superseded in this paper, EPJC 79 (2019) 20.The superseded preliminary plots can be found here. |

Figures | |

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Figure 1:
Distributions of the BDT output for background photons in the 200-220 GeV bin for the EB region. The black points show events from a sideband region of the photon isolation selection criteria, the blue-solid histogram shows the events in the signal region in simulated QCD multijet events and the red-dashed histogram represents events in the sideband region for simulated QCD multijet events. All three samples have their statistical uncertainties shown as error bars. |

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Figure 2:
Distributions of the BDT scores for an EB (left) and an EE (right) bin with photon $ {E_{\mathrm {T}}} $ between 200 - 220 GeV and $ | y^{\text jet} | < 1.5$. The points represent data, the blue histograms represent the fit results with the signal (cyan) and background (red) components displayed. The bottom panels show the ratio of the difference between the data and the fit to the statistical uncertainty in the data, along with the resulting reduced $\chi ^2$. |

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Figure 2-a:
Distributions of the BDT scores for an EB (left) and an EE (right) bin with photon $ {E_{\mathrm {T}}} $ between 200 - 220 GeV and $ | y^{\text jet} | < 1.5$. The points represent data, the blue histograms represent the fit results with the signal (cyan) and background (red) components displayed. The bottom panels show the ratio of the difference between the data and the fit to the statistical uncertainty in the data, along with the resulting reduced $\chi ^2$. |

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Figure 2-b:
Distributions of the BDT scores for an EB (left) and an EE (right) bin with photon $ {E_{\mathrm {T}}} $ between 200 - 220 GeV and $ | y^{\text jet} | < 1.5$. The points represent data, the blue histograms represent the fit results with the signal (cyan) and background (red) components displayed. The bottom panels show the ratio of the difference between the data and the fit to the statistical uncertainty in the data, along with the resulting reduced $\chi ^2$. |

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Figure 3:
Double differential cross sections for isolated photon production in photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The points show the measured values and their total uncertainties; the lines show the JETPHOX predictions with the NNPDF3.0 PDF set. |

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Figure 4:
The ratios of theoretical predictions to data for the double differential cross section for isolated photon production in four photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The error bars on data points represent the statistical uncertainty, while the hatched area shows the total experimental uncertainty. The errors on the ratio represent scale uncertainties, and the shaded regions represent the total theoretical uncertainties. |

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Figure 4-a:
The ratios of theoretical predictions to data for the double differential cross section for isolated photon production in four photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The error bars on data points represent the statistical uncertainty, while the hatched area shows the total experimental uncertainty. The errors on the ratio represent scale uncertainties, and the shaded regions represent the total theoretical uncertainties. |

png pdf |
Figure 4-b:
The ratios of theoretical predictions to data for the double differential cross section for isolated photon production in four photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The error bars on data points represent the statistical uncertainty, while the hatched area shows the total experimental uncertainty. The errors on the ratio represent scale uncertainties, and the shaded regions represent the total theoretical uncertainties. |

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Figure 4-c:
The ratios of theoretical predictions to data for the double differential cross section for isolated photon production in four photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The error bars on data points represent the statistical uncertainty, while the hatched area shows the total experimental uncertainty. The errors on the ratio represent scale uncertainties, and the shaded regions represent the total theoretical uncertainties. |

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Figure 4-d:
The ratios of theoretical predictions to data for the double differential cross section for isolated photon production in four photon rapidity bins, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The error bars on data points represent the statistical uncertainty, while the hatched area shows the total experimental uncertainty. The errors on the ratio represent scale uncertainties, and the shaded regions represent the total theoretical uncertainties. |

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Figure 5:
Triple differential cross sections for photon+jets production in two photon rapidity bins, $ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$, and two jet rapidity bins, $ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$. The points show the measured values with their total uncertainties, and the lines show the JETPHOX predictions with the NNPDF3.0 PDF set. |

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Figure 6:
The ratio of theoretical prediction to data for the triple differential cross section for photon+jets production in two photon rapidity ($ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$) and two jet rapidity ($ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$) bins. The error bars on the data points represent their statistical uncertainty, while the hatched area shows the total experimental uncertainty. The error bars on the ratios show the scale uncertainties, and the shaded area shows the total theoretical uncertainties. |

png pdf |
Figure 6-a:
The ratio of theoretical prediction to data for the triple differential cross section for photon+jets production in two photon rapidity ($ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$) and two jet rapidity ($ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$) bins. The error bars on the data points represent their statistical uncertainty, while the hatched area shows the total experimental uncertainty. The error bars on the ratios show the scale uncertainties, and the shaded area shows the total theoretical uncertainties. |

png pdf |
Figure 6-b:
The ratio of theoretical prediction to data for the triple differential cross section for photon+jets production in two photon rapidity ($ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$) and two jet rapidity ($ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$) bins. The error bars on the data points represent their statistical uncertainty, while the hatched area shows the total experimental uncertainty. The error bars on the ratios show the scale uncertainties, and the shaded area shows the total theoretical uncertainties. |

png pdf |
Figure 6-c:
The ratio of theoretical prediction to data for the triple differential cross section for photon+jets production in two photon rapidity ($ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$) and two jet rapidity ($ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$) bins. The error bars on the data points represent their statistical uncertainty, while the hatched area shows the total experimental uncertainty. The error bars on the ratios show the scale uncertainties, and the shaded area shows the total theoretical uncertainties. |

png pdf |
Figure 6-d:
The ratio of theoretical prediction to data for the triple differential cross section for photon+jets production in two photon rapidity ($ | y^{\gamma} | < 1.44$ and 1.57 $ < | y^{\gamma} | < 2.5$) and two jet rapidity ($ | y^{\text {jet}} | < 1.5$ and 1.5 $ < | y^{\text {jet}} | < 2.4$) bins. The error bars on the data points represent their statistical uncertainty, while the hatched area shows the total experimental uncertainty. The error bars on the ratios show the scale uncertainties, and the shaded area shows the total theoretical uncertainties. |

png pdf |
Figure 7:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-a:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-b:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-c:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-d:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-e:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-f:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-g:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

png pdf |
Figure 7-h:
JETPHOX predictions with different PDF sets are shown. Data are shown as black points, the error bars represent statistical uncertainties, while the hatched area represents the total experimental uncertainties. The theoretical uncertainty in the NNPDF3.0 prediction is shown as a shaded area. |

Tables | |

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Table 1:
Systematic uncertainties, in percent, for each source in the four photon rapidity regions, $ | y^{\gamma} | < 0.8$, 0.8 $ < | y^{\gamma} | < 1.44$, 1.57 $ < | y^{\gamma} | < 2.1$, and 2.1 $ < | y^{\gamma} | < 2.5$. The ranges, when quoted, indicate the variation over photon $ {E_{\mathrm {T}}} $ between 190-1000 GeV. |

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Table 2:
Measured and predicted double differential cross section for isolated photon production, along with the statistical and systematical uncertainties in the various $ {E_{\mathrm {T}}} $ and $y$ bins. Predictions use JETPHOX with the NNPDF3.0 PDF set. The ratio of the JETPHOX predictions to data are also presented, with the total uncertainty estimated assuming uncorrelated experimental and theoretical uncertainties. |

png pdf |
Table 3:
Measured and predicted triple differential cross section for photon+jets production, along with statistical and systematical uncertainties in the various $ {E_{\mathrm {T}}} $ and $y$ bins. Predictions are based on JETPHOX with the NNPDF3.0 PDF set. The ratio of the JETPHOX predictions to the data are also presented, with the total uncertainty estimated assuming uncorrelated experimental and theoretical uncertainties. |

Summary |

The differential cross sections for inclusive isolated photon and photon+jets production in proton-proton collisions at a center-of-mass energy of 13 TeV are measured with a data sample collected by the CMS experiment corresponding to an integrated luminosity of 2.26 fb$^{-1}$. The measurement of inclusive isolated photon production cross section is reported as a function of photon transverse momentum and rapidity. The photon+jets production cross section is reported as a function of photon transverse momentum, and photon and jet rapidities. The measurements are compared with theoretical predictions produced using the JETPHOX next-to-leading order calculations using different parton distribution functions. The theoretical predictions agree with the experimental measurements given statistical and systematic uncertainties. |

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Compact Muon Solenoid LHC, CERN |