CMS-SMP-16-003 ; CERN-EP-2018-167 | ||
Measurement of differential cross sections for inclusive isolated-photon and photon+jets production in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||
CMS Collaboration | ||
2 July 2018 | ||
Eur. Phys. J. C 79 (2019) 20 | ||
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 energy, for $E_{\mathrm{T}} > $ 190 GeV, and rapidity, for $| y | < $ 2.5. The cross section for photon+jets production is measured as a function of the photon transverse energy, for $E_{\mathrm{T}} > $ 190 GeV, the photon rapidity, for $| y | < $ 2.5, and the rapidity of the jet with highest transverse momentum, up to $| y | < $ 2.4. The experimental measurements are found to be in agreement with predictions from perturbative QCD. | ||
Links: e-print arXiv:1807.00782 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; |
Figures | |
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Figure 1:
Distributions of the BDT for background photons in the 200-220 GeV bin for the EB region. The points show events from a sideband region of the photon isolation selection criteria, the solid histogram shows the events in the signal region in simulated QCD multijet events, and the dashed histogram shows 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 output 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, and the solid histograms, approaching the data points, represent the fit results with the signal (dashed) and background (dotted) 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 $\chi ^2$ over degrees of freedom (dof). |
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Figure 2-a:
Distribution of the BDT output for an EB bin with photon $ {E_{\mathrm {T}}} $ between 200-220 GeV and $ {| y^{\text {jet}} |} < $ 1.5. The points represent data, and the solid histograms, approaching the data points, represent the fit results with the signal (dashed) and background (dotted) components displayed. The bottom panel shows the ratio of the difference between the data and the fit to the statistical uncertainty in the data, along with the resulting reduced $\chi ^2$ over degrees of freedom (dof). |
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Figure 2-b:
Distribution of the BDT output for an EE bin with photon $ {E_{\mathrm {T}}} $ between 200-220 GeV and $ {| y^{\text {jet}} |} < $ 1.5. The points represent data, and the solid histograms, approaching the data points, represent the fit results with the signal (dashed) and background (dotted) components displayed. The bottom panel shows the ratio of the difference between the data and the fit to the statistical uncertainty in the data, along with the resulting reduced $\chi ^2$ over degrees of freedom (dof). |
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Figure 3:
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 NLO JETPHOX predictions with the NNPDF3.0 PDF set. |
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Figure 4:
The ratios of theoretical NLO predictions to data for the differential cross sections 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, are shown. 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 ratio of theoretical NLO predictions to data for the differential cross sections for isolated-photon production, in photon rapidity bin $ {| y^{\gamma} |} < $ 0.8, is shown. 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-b:
The ratio of theoretical NLO predictions to data for the differential cross sections for isolated-photon production, in photon rapidity bin 0.8 $ < {| y^{\gamma} |} < $ 1.44, is shown. 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 ratio of theoretical NLO predictions to data for the differential cross sections for isolated-photon production, in photon rapidity bin 1.57 $ < {| y^{\gamma} |} < $ 2.1, is shown. 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 ratio of theoretical NLO predictions to data for the differential cross sections for isolated-photon production, in photon rapidity bin 2.1 $ < {| y^{\gamma} |} < $ 2.5, is shown. 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:
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 NLO JETPHOX predictions with the NNPDF3.0 PDF set. |
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Figure 6:
The ratios of theoretical NLO prediction to data for the differential cross sections 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, are shown. 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. |
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Figure 6-a:
The ratio of theoretical NLO prediction to data for the differential cross sections for photon+jets production in photon rapidity bin $ {| y^{\gamma} |} < $ 1.44 and jet rapidity bin $ {| y^{\text {jet}} |} < $ 1.5, are shown. 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. |
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Figure 6-b:
The ratio of theoretical NLO prediction to data for the differential cross sections for photon+jets production in photon rapidity bin $ {| y^{\gamma} |} < $ 1.44 and jet rapidity bin 1.5 $ < {| y^{\text {jet}} |} < $ 2.4, are shown. 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. |
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Figure 6-c:
The ratio of theoretical NLO prediction to data for the differential cross sections for photon+jets production in photon rapidity bin 1.57 $ < {| y^{\gamma} |} < $ 2.5 and jet rapidity bin $ {| y^{\text {jet}} |} < $ 1.5, are shown. 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. |
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Figure 6-d:
The ratio of theoretical NLO prediction to data for the differential cross sections for photon+jets production in photon rapidity bin 1.57 $ < {| y^{\gamma} |} < $ 2.5 and jet rapidity bin 1.5 $ < {| y^{\text {jet}} |} < $ 2.4, are shown. 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. |
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Figure 7:
Ratios of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for inclusive isolated-photons (top four panels) and photon+jets (four bottom panels). Data are shown as 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. |
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Figure 7-a:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for inclusive isolated-photons. Data are shown as 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. |
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Figure 7-b:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for inclusive isolated-photons. Data are shown as 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. |
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Figure 7-c:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for inclusive isolated-photons. Data are shown as 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. |
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Figure 7-d:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for inclusive isolated-photons. Data are shown as 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. |
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Figure 7-e:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for photon+jets. Data are shown as 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. |
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Figure 7-f:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for photon+jets. Data are shown as 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. |
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Figure 7-g:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for photon+jets. Data are shown as 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. |
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Figure 7-h:
Ratio of JETPHOX NLO predictions to data for various PDF sets as a function of photon $ {E_{\mathrm {T}}} $ for photon+jets. Data are shown as 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:
Impact on cross sections, in percent, for each systematic uncertainty 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 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 at NLO with the NNPDF3.0 PDF set. The ratio of the JETPHOX predictions to data are listed in the last column, with the total uncertainty estimated assuming uncorrelated experimental and theoretical uncertainties. |
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Table 3:
Measured and predicted 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 at NLO with the NNPDF3.0 PDF set. The ratio of the JETPHOX predictions to the data are listed in the last column, 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 measurements of inclusive isolated-photon production cross sections are presented as functions of photon transverse energy and rapidity. The photon+jets production cross sections are presented as functions of photon transverse energy, 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 within the statistical and systematic uncertainties. For low to middle range in photon $ E_{\mathrm{T}} $, where the experimental uncertainties are smaller or comparable to theoretical uncertainties, these measurements provide the potential to further constrain the proton PDFs. The agreement between data and theory, and the new next-to-next-to-leading-order (NNLO) calculations [46] motivate the use of additional measurements to better estimate the gluon and other PDFs. |
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Compact Muon Solenoid LHC, CERN |