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Compact Muon Solenoid
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CMS-SMP-14-023 ; CERN-EP-2016-231
Measurements of differential cross sections for associated production of a W boson and jets in proton-proton collisions at $ \sqrt{s} = $ 8 TeV
Phys. Rev. D 95 (2017) 052002
Abstract: Differential cross sections for a W boson produced in association with jets are measured in a data sample of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the CMS detector and corresponding to an integrated luminosity of 19.6 fb$^{-1}$. The W bosons are identified through their decay mode $\mathrm{ W }\to \mu\nu$. The cross sections are reported as functions of jet multiplicity, transverse momenta, and the scalar sum of jet transverse momenta ($H_{\mathrm{T}}$) for different jet multiplicities. Distributions of the angular correlations between the jets and the muon are examined, as well as the average number of jets as a function of $H_{\mathrm{T}}$ and as a function of angular variables. The measured differential cross sections are compared with tree-level and higher-order recent event generators, as well as next-to-leading-order and next-to-next-to-leading-order theoretical predictions. The agreement of the generators with the measurements builds confidence in their use for the simulation of W+jets background processes in searches for new physics at the LHC.
Figures & Tables Summary References CMS Publications
Figures

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Figure 1:
Distribution of inclusive jet multiplicity, for reconstructed data (points) and simulated signal and backgrounds (histograms). The ratio of simulated and measured data events is shown below the distribution. The data points are shown with statistical error bars. The error band represents the total statistical and systematic uncertainty.

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Figure 2:
Systematic uncertainties in the measured cross section as a function of jet multiplicity, including uncertainties due to jet energy scale (JES), background normalization, b tagging efficiency, finite number of simulated events used to construct the response matrix (MC stat), and other systematic uncertainties mentioned in Section {systematics}. Statistical uncertainty of the unfolded data and total uncertainty in the measured cross section are also shown.

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Figure 3:
Measured cross section versus exclusive (left) and inclusive (right) jet multiplicity, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions), for which we currently have predictions only up to W+4 jets. Black circular markers with the gray hatched band represent the unfolded data measurement and its total uncertainty. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 3-a:
Measured cross section versus exclusive jet multiplicity, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions), for which we currently have predictions only up to W+4 jets. Black circular markers with the gray hatched band represent the unfolded data measurement and its total uncertainty. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 3-b:
Measured cross section versus inclusive jet multiplicity, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions), for which we currently have predictions only up to W+4 jets. Black circular markers with the gray hatched band represent the unfolded data measurement and its total uncertainty. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 4:
Cross sections differential in the transverse momenta of the four leading jets, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 4-a:
Cross section differential in the transverse momenta of the first leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 4-b:
Cross section differential in the transverse momenta of the second leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 4-c:
Cross section differential in the transverse momenta of the third leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 4-d:
Cross section differential in the transverse momenta of the fourth leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 5:
Cross sections differential in $ {H_{\mathrm {T}}} $ for inclusive jet multiplicities 1-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 5-a:
Cross section differential in $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 1, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 5-b:
Cross section differential in $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 5-c:
Cross section differential in $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 5-d:
Cross section differential in $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 6:
Cross sections differential in dijet ${p_{\mathrm {T}}}$ (calculated from the two leading jets) for inclusive jet multiplicities 2-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 6-a:
Cross section differential in dijet ${p_{\mathrm {T}}}$ (calculated from the two leading jets) for inclusive jet multiplicity 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 6-b:
Cross section differential in dijet ${p_{\mathrm {T}}}$ (calculated from the two leading jets) for inclusive jet multiplicity 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 6-c:
Cross section differential in dijet ${p_{\mathrm {T}}}$ (calculated from the two leading jets) for inclusive jet multiplicity 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 7:
Cross sections differential in dijet invariant mass (calculated from the two leading jets) for inclusive jet multiplicities 2-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 7-a:
Cross sections differential in dijet invariant mass (calculated from the two leading jets) for inclusive jet multiplicities 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 7-b:
Cross sections differential in dijet invariant mass (calculated from the two leading jets) for inclusive jet multiplicities 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 7-c:
Cross sections differential in dijet invariant mass (calculated from the two leading jets) for inclusive jet multiplicities 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 8:
Cross sections differential in the pseudorapidities of the four leading jets, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 8-a:
Cross section differential in the pseudorapidities of the first leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 8-b:
Cross section differential in the pseudorapidities of the second leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 8-c:
Cross section differential in the pseudorapidities of the third leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 8-d:
Cross section differential in the pseudorapidities of the fourth leading jet, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, BLACKHAT+SHERPA, and NNLO inclusive one-jet production (indicated as $\rm N_{jetti}$ NNLO). The BLACKHAT+SHERPA and NNLO predictions are corrected for hadronization and multiple-parton interaction effects. Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 9:
Cross sections differential in $\Delta y(j_1,j_2)$ for inclusive jet multiplicities 2-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 9-a:
Cross section differential in $\Delta y(j_1,j_2)$ for inclusive jet multiplicities 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 9-b:
Cross section differential in $\Delta y(j_1,j_2)$ for inclusive jet multiplicities 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 9-c:
Cross section differential in $\Delta y(j_1,j_2)$ for inclusive jet multiplicities 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 10:
Cross sections differential in $\Delta y(j_1,j_3)$ (left) and $\Delta y(j_2,j_3)$ (right) for an inclusive jet multiplicity of 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 10-a:
Cross section differential in $\Delta y(j_1,j_3)$ for an inclusive jet multiplicity of 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 10-b:
Cross section differential in $\Delta y(j_2,j_3)$ for an inclusive jet multiplicity of 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 11:
Cross sections differential in $\Delta y(j_F,j_B)$ for inclusive jet multiplicities 2-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 11-a:
Cross section differential in $\Delta y(j_F,j_B)$ for inclusive jet multiplicity 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 11-b:
Cross section differential in $\Delta y(j_F,j_B)$ for inclusive jet multiplicity 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 11-c:
Cross section differential in $\Delta y(j_F,j_B)$ for inclusive jet multiplicity 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 12:
Cross sections differential in $\Delta \phi (j_1,j_2)$ (left) and $\Delta \phi (j_F,j_B)$ (right) for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 12-a:
Cross section differential in $\Delta \phi (j_1,j_2)$ for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 12-b:
Cross section differential in $\Delta \phi (j_F,j_B)$ for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 13:
Cross section differential in $\Delta R(j_{1},j_{2})$ for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 14:
Cross sections differential in $\Delta \phi (j_{n},\mu )$ for inclusive jet multiplicities $n = $ 1-4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 14-a:
Cross section differential in $\Delta \phi (j_{n},\mu )$ for inclusive jet multiplicity $n = $ 1, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 14-b:
Cross section differential in $\Delta \phi (j_{n},\mu )$ for inclusive jet multiplicity $n = $ 2, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 14-c:
Cross section differential in $\Delta \phi (j_{n},\mu )$ for inclusive jet multiplicity $n = $ 3, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 14-d:
Cross section differential in $\Delta \phi (j_{n},\mu )$ for inclusive jet multiplicity $n = $ 4, compared to the predictions of MadGraph, MadGraph-5-aMC@NLO, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 15:
Average number of jets $< N_\text {jets} > $ as a function of $ {H_{\mathrm {T}}} $ for inclusive jet multiplicities 1-2 (top row) and as a function of $\Delta y(j_1,j_2)$ and $\Delta y(j_F,j_B)$ for an inclusive jet multiplicity of 2 (bottom row), compared to the predictions of MadGraph, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 15-a:
Average number of jets $< N_\text {jets} > $ as a function of $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 1, compared to the predictions of MadGraph, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 15-b:
Average number of jets $< N_\text {jets} > $ as a function of $ {H_{\mathrm {T}}} $ for inclusive jet multiplicity 2, compared to the predictions of MadGraph, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 15-c:
Average number of jets $< N_\text {jets} > $ as a function of $\Delta y(j_1,j_2)$ for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.

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Figure 15-d:
Average number of jets $< N_\text {jets} > $ as a function of $\Delta y(j_F,j_B)$ for an inclusive jet multiplicity of 2, compared to the predictions of MadGraph, SHERPA-2, and BLACKHAT+SHERPA (corrected for hadronization and multiple-parton interactions). Black circular markers with the gray hatched band represent the unfolded data measurements and their total uncertainties. Overlaid are the predictions together with their uncertainties. The lower plots show the ratio of each prediction to the unfolded data.
Tables

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Table 1:
Number of events in data and simulation as a function of exclusive reconstructed jet multiplicity. The purity is the number of simulated signal events (W+jets) divided by the total number of simulated signal and background events (Total). The ratio is the total number of simulated signal and background events divided by the number of data events.
Summary
Differential cross sections for a W boson produced in association with jets in pp collisions at a center-of-mass energy of 8 TeV were measured. The data correspond to an integrated luminosity of 19.6 fb$^{-1}$ and were collected with the CMS detector at the LHC. Cross sections measured using the muonic decay mode of the W boson were presented as functions of the jet multiplicity, the transverse momenta and pseudorapidities of the four leading jets, $H_{\mathrm{T}}$ for jet multiplicities up to four, and the dijet and invariant mass. Cross sections were also presented as functions of several angular correlation variables: rapidity difference, azimuthal angle difference, and $\Delta R $ between $p_{\mathrm{T}}$-ordered and rapidity-ordered jets, and azimuthal angle difference between the muon and the leading jet. The dependence of the average number of jets on $H_{\mathrm{T}}$ and on rapidity differences between jets was examined. The results were corrected for detector effects by means of regularized unfolding and compared with particle-level simulated predictions using MadGraph5+PYTHIA6; SHERPA-2 and MadGraph-MC@NLO+PYTHIA8 (multileg NLO); BLACKHAT+SHERPA (NLO); and $N_\text{jetti}$ NNLO. The predictions generally describe the jet multiplicity within the uncertainties, with increasing deviations observed in SHERPA-2 for jet multiplicities greater than 4. The cross sections differential in the $p_{\mathrm{T}}$ of the three leading jets are overestimated by MadGraph5+PYTHIA6 in a region of intermediate $p_{\mathrm{T}}$, and by SHERPA-2 at low $p_{\mathrm{T}}$. The cross sections as functions of jet $p_{\mathrm{T}}$ predicted by BLACKHAT+SHERPA and by MadGraph-MC@NLO+PYTHIA8 agree with the measurements within uncertainties. The cross section as a function of $H_{\mathrm{T}}$ is underestimated by BLACKHAT+SHERPA for $N_\text{jets} \geq $ 1 because the contribution from W+$ {\geq}3$ jets is missing from an NLO prediction of W+$ {\geq}$ 1 jet. The corresponding predictions from SHERPA-2 overestimate the cross section, particularly at high $H_{\mathrm{T}}$. The predictions for the jet $|{\eta}|$ distribution deviate from the measurements for large values of $|{\eta}|$, as do the predictions for the angular correlation distributions in rapidity for large rapidity differences. Improvement in describing the data at high rapidity difference and at low azimuthal angle difference between muon and jet is observed when considering MadGraph-MC@NLO+PYTHIA8 versus tree-level MadGraph5+PYTHIA6. The distribution of the azimuthal angle between the muon and the leading jet is not well modeled by BLACKHAT+SHERPA for $N_\text{jets} \geq $ 1. The predictions for the correlation distributions in azimuthal angle between jets agree with the measurements, as well as the dependence of the average number of jets on angular correlation variables and on $H_{\mathrm{T}}$. The NNLO predictions for W+1 jet production were compared with the measured cross sections differential in leading jet $p_{\mathrm{T}}$, $H_{\mathrm{T}}$, and leading jet $|{\eta}|$ and agree with data within uncertainties.
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