CMS-SMP-13-012

CMS-SMP-13-012 ; CERN-EP-2016-093
Measurement of electroweak production of a W boson and two forward jets in proton-proton collisions at $\sqrt{s} =$ 8 TeV
CMS Collaboration
23 July 2016
JHEP 11 (2016) 147
Abstract: A measurement is presented of the cross section for the electroweak production of a W boson in association with two jets in proton-proton collisions at a center-of-mass energy of 8 TeV. The data set was collected with the CMS detector and corresponds to an integrated luminosity of 19.3 fb $^{-1}$ . The measured fiducial cross section for W bosons decaying to electrons or muons and for $p_{\mathrm{T}}^{\mathrm{j1}} >$ 60 GeV, $p_{\mathrm{T}}^{\mathrm{j2}} >$ 50 GeV, $\|{\eta^{\mathrm{j}}} \| <$ 4.7, and ${m_{\mathrm{jj}}} >$ 1000 GeV is 0.42 $\pm$ 0.04 (stat) $\pm$ 0.09 (syst) $\pm$ 0.01 (lumi) pb. This result is consistent with the standard model leading-order prediction of 0.50 $\pm$ 0.02 (scale) $\pm$ 0.02 (PDF) pb obtained with MADGRAPH5-aMC@NLO 2.1 interfaced to PYTHIA 6.4. This is the first cross section measurement for this process.
Links: e-print arXiv:1607.06975 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Representative diagrams for EW $\ell \nu \mathrm {jj}$ productions at the LHC: (a) bremsstrahlung, (b) VBF, and (c) multiperipheral processes.
png pdf	Figure 1-a: Representative diagrams for EW $\ell \nu \mathrm {jj}$ productions at the LHC: (a) bremsstrahlung, (b) VBF, and (c) multiperipheral processes.
png pdf	Figure 1-b: Representative diagrams for EW $\ell \nu \mathrm {jj}$ productions at the LHC: (a) bremsstrahlung, (b) VBF, and (c) multiperipheral processes.
png pdf	Figure 1-c: Representative diagrams for EW $\ell \nu \mathrm {jj}$ productions at the LHC: (a) bremsstrahlung, (b) VBF, and (c) multiperipheral processes.
png pdf	Figure 2: Comparison of the distributions of BDT discriminant output between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 2-a: Comparison of the distributions of BDT discriminant output between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 2-b: Comparison of the distributions of BDT discriminant output between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 3: Comparison of the distributions of the leading jet ${p_{\mathrm {T}}}$ between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 3-a: Comparison of the distributions of the leading jet ${p_{\mathrm {T}}}$ between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 3-b: Comparison of the distributions of the leading jet ${p_{\mathrm {T}}}$ between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 4: Comparison of the distributions of $\Delta \eta$ between the two leading jets between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 4-a: Comparison of the distributions of $\Delta \eta$ between the two leading jets between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 4-b: Comparison of the distributions of $\Delta \eta$ between the two leading jets between data and simulation for the electron (a) and muon (b) channels with ${m_{\mathrm {jj}}} >$ 1000 GeV.
png pdf	Figure 5 : Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -a: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -b: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -c: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -d: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -e: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.
png pdf	Figure 5 -f: Distribution of the two-jet invariant mass ${m_{\mathrm {jj}}}$ for electron (a,b,c) and muon (d,e,f) channels. Fitted projections of signal and background processes are plotted as shaded regions (a,d). The ${m_{\mathrm {jj}}}$ distributions are shown after subtraction of all components except the EW $\mathrm{ W }$ +2-jets process (b,e). Finally, the $(\text {data} - \text {fit})/\text {uncertainty}$ distributions are shown (c,f). Here the error bars represent the statistical uncertainties of the data.

Tables
png pdf	Table 1: Summary of selection criteria.
png pdf	Table 2: The expected event yields and the ratio of the measured and expected yields extracted from the maximum-likelihood fit to data.
png pdf	Table 3: Sources of systematic uncertainties and the magnitude of their effect on the fiducial cross section.
png pdf	Table 4: The measured values for the EW $\mathrm{ W } (\to \ell \nu )$ +2-jets fiducial cross section.

Summary

A measurement has been performed of the cross section for the electroweak production of W bosons produced in association with two forward jets in proton-proton collisions. The W bosons were identified through their decay to electrons and muons. The data set was collected by the CMS experiment and corresponds to an integrated luminosity of 19.2 (19.3)

$\pm$ 0.5 fb

$^{-1}$ in the electron (muon) channel at

$\sqrt{s} =$ 8 TeV. The measured value of the fiducial electroweak W+2-jets cross section, for W bosons decaying to electrons or muons and for

$p_{\mathrm{T}}^{\mathrm{j1}} >$ 60 GeV,

$p_{\mathrm{T}}^{\mathrm{j2}} >$ 50 GeV,

$|{\eta^{\mathrm{j}}} | <$ 4.7, and

${m_{\mathrm{jj}}} >$ 1000 GeV, is 0.42

$\pm$ 0.04 (stat)

$\pm$ 0.09 (syst)

$\pm$ 0.01 (lumi) pb, consistent with the SM LO prediction of 0.50

$\pm$ 0.02 (scale)

$\pm$ 0.02 (PDF) obtained via MADGRAPH5-aMC@NLO 2.1 interfaced with PYTHIA 6.4. This is the first measurement of the cross section for electroweak W+2-jets production.

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