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| CMS-PAS-FTR-18-005 | ||
| Study of $\mathrm{ W^{\pm}W^{\pm} }$ production via vector boson scattering at the HL-LHC with the upgraded CMS detector | ||
| CMS Collaboration | ||
| November 2018 | ||
| Abstract: The prospects for the study of $\mathrm{W^{\pm}W^{\pm}} {\text{jj}}$ final states, produced in proton-proton collisions at centre-of-mass energy of 14 TeV via vector boson scattering (VBS), with the upgraded CMS detector at the High-Luminosity LHC (HL-LHC) are presented. The W bosons are detected via their leptonic decays: $\mathrm{ W \rightarrow e\nu }$ or $\mu\nu$. The results from a study using a full simulation of the upgraded detector along with an average number of 200 proton-proton interactions per bunch crossing are presented in terms of the precision of the cross section measurement as a function of the total integrated luminosity. The significance of the polarized cross section measurement is also discussed. | ||
| Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Representative Feynman diagrams for $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ electroweak production in proton-proton collisions: (left) t-channel Higgs boson exchange, (middle) t-channel $\mathrm{Z}/\gamma $ exchange with triple gauge couplings, (right) quartic gauge coupling. |
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Figure 2:
Shape comparisons for signal and background processes. Left: Invariant mass of the two leading jets. Right: The difference in pseudorapidity between them. |
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Figure 2-a:
Shape comparison for signal and background processes: Invariant mass of the two leading jets. |
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Figure 2-b:
Shape comparison for signal and background processes: Difference in pseudorapidity between the two leading jets. |
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Figure 3:
Shape comparisons for the signal and background processes. Left: The maximum of the Zeppenfeld variable for leptons. Right: Missing transverse momentum. |
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Figure 3-a:
Shape comparison for signal and background processes: Maximum of the Zeppenfeld variable for leptons. |
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Figure 3-b:
Shape comparison for signal and background processes: Missing transverse momentum. |
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Figure 4:
Left: The distribution of the invariant mass of the two leading jets after the selection requirements for an integrated luminosity of 3000 fb$^{-1}$. Right: The estimated uncertainty in the EWK $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ cross section measurement as a function of the integrated luminosity (with YR18 systematic uncertainties). |
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Figure 4-a:
The distribution of the invariant mass of the two leading jets after the selection requirements for an integrated luminosity of 3000 fb$^{-1}$. |
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Figure 4-b:
The estimated uncertainty in the EWK $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ cross section measurement as a function of the integrated luminosity (with YR18 systematic uncertainties). |
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Figure 5:
The shape comparison of the LL, LT and TT components in the distribution of the azimuthal angle difference between the two leading jets for the VBS $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ process for dijet invariant mass between 500 to 1100 GeV (left), and above 1100 GeV (right). |
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Figure 5-a:
The shape comparison of the LL, LT and TT components in the distribution of the azimuthal angle difference between the two leading jets for the VBS $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ process for dijet invariant mass between 500 to 1100 GeV. |
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Figure 5-b:
The shape comparison of the LL, LT and TT components in the distribution of the azimuthal angle difference between the two leading jets for the VBS $ {\mathrm {W}}^{\pm} {\mathrm {W}}^{\pm} $ process for dijet invariant mass above 1100 GeV. |
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Figure 6:
Distributions of the azimuthal angle difference between the two leading jets for dijet invariant mass in the range 500-1100 GeV (left) and above 1100 GeV (right). Stacked contributions from the signal and various backgrounds are shown. |
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Figure 6-a:
Distribution of the azimuthal angle difference between the two leading jets for dijet invariant mass in the range 500-1100 GeV. Stacked contributions from the signal and various backgrounds are shown. |
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Figure 6-b:
Distribution of the azimuthal angle difference between the two leading jets for dijet invariant mass above 1100 GeV. Stacked contributions from the signal and various backgrounds are shown. |
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Figure 7:
Significance of the observation of the scattering of a pair of longitudinally polarized W bosons as a function of the integrated luminosity (with YR18 systematic uncertainties). |
| Tables | |
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Table 1:
Expected yields for signal and background contributions for ${\cal L} = $ 3000 fb$^{-1}$. |
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Table 2:
The systematic uncertainties considered in this analysis and their impact on the signal strength for two different integrated luminosities. For comparison, the expected statistical uncertainty is shown in the first row. |
| Summary |
| The prospects for the study of the $\mathrm{W}^{\pm}\mathrm{W}^{\pm} \text{jj}$ final states produced via vector boson scattering (VBS) in pp collisions at the HL-LHC have been presented. The signal and background events were generated with a full simulation of the response of the Phase 2 upgraded CMS detector. The W bosons are detected via their leptonic decays into $\mathrm{e}\nu$ or $\mu\nu$. It is shown that the total experimental uncertainty in the VBS $\mathrm{W}^{\pm}\mathrm{W}^{\pm}$ cross section measurement decreases by more than a factor of two when moving from a total integrated luminosity of 300 to 3000 fb$^{-1}$, down to about 3%, and can be decreased even further if the results from CMS and ATLAS experiments are combined. The analysis demonstrates the sensitivity for measuring the longitudinally polarized component of the $\mathrm{W}^{\pm}\mathrm{W}^{\pm}$ VBS production. The expected significance for an integrated luminosity of 3000 fb$^{-1}$ is estimated to be 2.7 standard deviations, and can exceed a value of 3 for a combination of the CMS and ATLAS measurements. |
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