CMS-B2G-18-006

CMS-B2G-18-006 ; CERN-EP-2019-110
Combination of CMS searches for heavy resonances decaying to pairs of bosons or leptons
CMS Collaboration
31 May 2019
Phys. Lett. B 798 (2019) 134952
Abstract: A statistical combination of searches for heavy resonances decaying to pairs of bosons or leptons is presented. The data correspond to an integrated luminosity of 35.9 fb$^{-1}$ collected during 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data are found to be consistent with expectations from the standard model background. Exclusion limits are set in the context of models of spin-1 heavy vector triplets and of spin-2 bulk gravitons. For mass-degenerate W' and Z' resonances that predominantly couple to the standard model gauge bosons, the mass exclusion at 95% confidence level of heavy vector bosons is extended to 4.5 TeV as compared to 3.8 TeV determined from the best individual channel. This excluded mass increases to 5.0 TeV if the resonances couple predominantly to fermions.
Links: e-print arXiv:1906.00057 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ;

Figures & Tables	Summary	Additional Figures	References	CMS Publications

Figures
png pdf	Figure 1: Observed and expected 95% CL upper limits on the product of the cross section and branching fraction of a spin-1 (left) or spin-2 resonance (right) decaying to a pair of SM bosons.
png pdf	Figure 1-a: Observed and expected 95% CL upper limits on the product of the cross section and branching fraction of a spin-1 resonance decaying to a pair of SM bosons.
png pdf	Figure 1-b: Observed and expected 95% CL upper limits on the product of the cross section and branching fraction of a spin-2 resonance decaying to a pair of SM bosons.
png pdf	Figure 2: Observed and expected 95% CL upper limits on the W' (left) and Z' cross section (right) as a function of the W' and Z' resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the VV and VH channels considered. The expected limits in individual channels are represented by the colored dashed lines. The solid curves surrounded by the shaded areas show the cross sections predicted by the HVT model B and their uncertainties.
png pdf	Figure 2-a: Observed and expected 95% CL upper limits on the W' cross section as a function of the resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the VV and VH channels considered. The expected limits in individual channels are represented by the colored dashed lines. The solid curves surrounded by the shaded areas show the cross sections predicted by the HVT model B and their uncertainties.
png pdf	Figure 2-b: Observed and expected 95% CL upper limits on the Z' cross section as a function of the resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the VV and VH channels considered. The expected limits in individual channels are represented by the colored dashed lines. The solid curves surrounded by the shaded areas show the cross sections predicted by the HVT model B and their uncertainties.
png pdf	Figure 3: Observed and expected 95% CL upper limits on cross sections as a function of the HVT triplet mass for the combination of all channels in the HVT model B (left) and model A (right). The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limit. The solid curves surrounded by the shaded areas show the cross sections predicted by HVT models A and B and their uncertainties.
png pdf	Figure 3-a: Observed and expected 95% CL upper limits on cross sections as a function of the HVT triplet mass for the combination of all channels in the HVT model B. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limit. The solid curves surrounded by the shaded areas show the cross sections predicted by the HVT model with uncertainties.
png pdf	Figure 3-b: Observed and expected 95% CL upper limits on cross sections as a function of the HVT triplet mass for the combination of all channels in the HVT model A. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limit. The solid curves surrounded by the shaded areas show the cross sections predicted by the HVT model with uncertainties.
png pdf	Figure 4: Observed exclusion limits on the couplings of heavy vector resonances to fermions and SM vector bosons and the Higgs boson for the statistical combination (solid lines) of the dilepton (dotted lines) and diboson channels (dashed lines). Three resonance masses hypotheses (3.0, 4.0, and 4.5 TeV) are considered. The hatched bands indicate the regions excluded. The areas bounded by the thin gray contour lines correspond to regions where the resonance widths ($\Gamma _{\mathrm{V}'}$) are predicted to be larger than the average experimental resolution (5%).
png pdf	Figure 5: Observed and expected 95% CL upper limit on the cross section of the spin-2 bulk graviton as a function of its mass for the statistical combination of the WW, ZZ, and HH channels. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limit. The solid curve and its shaded area represent the cross section derived with the parameter $ {\hat{\kappa}} =$ 0.5 and the associated uncertainty.

Tables
png pdf	Table 1: Summary of the main selections that guarantee the exclusivity between individual final states. The symbol $\ell $ represents an electron or a muon; $\tau $ leptons are considered separately. The AK4 b jets are additional b tagged AK4 jets that do not geometrically overlap with AK8 jets. The symbol "--'' implies that no selection is applied.
png pdf	Table 2: Summary of the main systematic uncertainties. The second column reports whether a systematic uncertainty is considered fully correlated or not across different channels. The third column indicates whether the uncertainty affects the yield, the shape of the distributions, or both, or if it induces migration (migr.) effects across search regions. The fourth column reports the smallest and largest effect of the uncertainty in either the yield or the signal shape parameters. The symbols "s'', "b'' indicate that the uncertainty affects the signal, the main backgrounds of the analysis, respectively. The treatment of non-dominant backgrounds is often different and not reported here. The symbol "f'' indicates that the parameters are not constrained, or associated with large uncertainties as in the case of multi-dimensional fits. The entries labeled with "t'' are treated differently depending on the interpretation of the exclusion limit, as discussed in Section 7. Uncertainties marked with "--'' are not applicable or are negligible.

Summary

A statistical combination of searches for heavy resonances decaying into pairs of vector bosons, a vector boson and a Higgs boson, two Higgs bosons, or pairs of leptons, has been presented. The results are based on data collected by the CMS experiment at $\sqrt{s} = $ 13 TeV during 2016 corresponding to an integrated luminosity of 35.9 fb$^{-1}$. In models with warped extra dimensions, upper limits of up to 1.1 fb are set at 95% confidence level on the production cross section of the spin-2 bulk graviton. For models with a triplet of narrow spin-1 resonances, heavy vector bosons with masses below 5.0 and 4.5 TeV are excluded at 95% confidence level in models where the W' and Z' bosons couple predominantly to fermions and bosons, respectively. In the latter, the statistical combination extends the exclusion limit by 700 GeV as compared to the best individual channel.

Additional Figures
png pdf	Additional Figure 2: Observed and expected 95% CL upper limits on the product of the bulk graviton cross section and the $\text {G}\to {\mathrm {W}} {\mathrm {W}}$ branching fraction as a function of the G resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant WW channels. The expected limits in individual channels are represented by the colored dashed lines.
png pdf	Additional Figure 3: Observed and expected 95% CL upper limits on the product of the W' cross section and the $ {\mathrm {W}'} \to {\mathrm {W}} {\mathrm {Z}} $ branching fraction as a function of the W' resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant WZ channels. The expected limits in individual channels are represented by the colored dashed lines.
png pdf	Additional Figure 4: Observed and expected 95% CL upper limits on the product of the bulk graviton cross section and the $\text {G}\to {\mathrm {Z}} {\mathrm {Z}} $ branching fraction as a function of the G resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant ZZ channels. The expected limits in individual channels are represented by the colored dashed lines.
png pdf	Additional Figure 5: Observed and expected 95% CL upper limits on the product of the W' cross section and the $ {\mathrm {W}'} \to {\mathrm {W}} {\mathrm {H}} $ branching fraction as a function of the W' resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant WH channels. The expected limits in individual channels are represented by the colored dashed lines.
png pdf	Additional Figure 6: Observed and expected 95% CL upper limits on the product of the Z' cross section and the $ {\mathrm {Z}'} \to {\mathrm {Z}} {\mathrm {H}} $ branching fraction as a function of the Z' resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant $ {\mathrm {Z}} {\mathrm {H}} $ channels. The expected limits in individual channels are represented by the colored dashed lines.
png pdf	Additional Figure 7: Observed and expected 95% CL upper limits on the product of the bulk graviton cross section and the $\text {G}\to {\mathrm {H}} {\mathrm {H}} $ branching fraction as a function of the G resonance mass. The inner green and outer yellow bands represent the ${\pm}$1 and ${\pm}$2 standard deviation variations on the expected limits of the statistical combination of the resonant $ {\mathrm {H}} {\mathrm {H}} $ channels. The expected limits in individual channels are represented by the colored dashed lines.

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