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| CMS-B2G-16-016 ; CERN-EP-2017-090 | ||
| Searches for W' bosons decaying to a top quark and a bottom quark in proton-proton collisions at 13 TeV | ||
| CMS Collaboration | ||
| 13 June 2017 | ||
| JHEP 08 (2017) 029 | ||
| Abstract: Searches are presented for heavy gauge bosons decaying into a top and a bottom quark in data collected by the CMS experiment at $ \sqrt{s} = $ 13 TeV that correspond to an integrated luminosity of 2.2 and 2.6 fb$^{-1}$ in the leptonic and hadronic analyses, respectively. Two final states are analyzed, one containing a single electron, or muon, and missing transverse momentum, and the other containing multiple jets and no electrons or muons. No evidence is found for a right-handed W' boson ($\mathrm{W}_{R}'$) and the combined analyses exclude at 95% confidence level $\mathrm{W}_{R}'$ with masses below 2.4 TeV if $ M_{\mathrm{W}_{R}'} \gg M_{\nu_\mathrm{R}} $ (mass of the right handed neutrino), and below 2.6 TeV if $ M_{\mathrm{W}_{R}'} < M_{\nu_\mathrm{R}} $. The results provide the most stringent limits for right-handed W' bosons in the top and bottom quark decay channel. | ||
| Links: e-print arXiv:1706.04260 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distributions from the leptonic analysis in the 1 b tag (upper) and 2 b tag (lower) categories, for the electron (left) and muon (right) channels. The "LF'' and "HF'' notations indicate the light- and heavy-flavor components of the W+jets contribution, respectively. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and background samples are normalized to the integrated luminosity of the analyzed data set. The distributions are shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 1-a:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution from the leptonic analysis in the 1 b tag category, for the electron channel. The "LF'' and "HF'' notations indicate the light- and heavy-flavor components of the W+jets contribution, respectively. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and background samples are normalized to the integrated luminosity of the analyzed data set. The distribution is shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 1-b:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution from the leptonic analysis in the 1 b tag category, for the muon channel. The "LF'' and "HF'' notations indicate the light- and heavy-flavor components of the W+jets contribution, respectively. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and background samples are normalized to the integrated luminosity of the analyzed data set. The distribution is shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 1-c:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution from the leptonic analysis in the 2 b tag category, for the electron channel. The "LF'' and "HF'' notations indicate the light- and heavy-flavor components of the W+jets contribution, respectively. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and background samples are normalized to the integrated luminosity of the analyzed data set. The distribution is shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 1-d:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution from the leptonic analysis in the 2 b tag category, for the muon channel. The "LF'' and "HF'' notations indicate the light- and heavy-flavor components of the W+jets contribution, respectively. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and background samples are normalized to the integrated luminosity of the analyzed data set. The distribution is shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 2:
Reconstructed $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution from the hadronic analysis. The simulated $ {\mathrm{ W } '_\mathrm {R}} $ signal and backgrounds are normalized to the integrated luminosity of the analyzed data set. The distribution is shown after the application of all selections. The 68% uncertainty in the background estimate includes all contributions to the predicted background, while the total uncertainty is the combined uncertainty of the background and data. |
png pdf |
Figure 3:
The 95% CL upper limit on the $ {\mathrm{ W } '_\mathrm {R}} $ boson production cross section, separately for the leptonic (upper) and hadronic (lower) analyses. Masses for which the theoretical cross section is above the observed upper limit are excluded at 95% CL. |
png pdf |
Figure 3-a:
The 95% CL upper limit on the $ {\mathrm{ W } '_\mathrm {R}} $ boson production cross section, for the leptonic analysis. Masses for which the theoretical cross section is above the observed upper limit are excluded at 95% CL. |
png pdf |
Figure 3-b:
The 95% CL upper limit on the $ {\mathrm{ W } '_\mathrm {R}} $ boson production cross section, for the hadronic analysis. Masses for which the theoretical cross section is above the observed upper limit are excluded at 95% CL. |
png pdf |
Figure 4:
The 95% CL upper limit on the $ {\mathrm{ W } '_\mathrm {R}} $ boson production cross section for the combined leptonic and hadronic analyses. Masses for which the theoretical cross section is above the observed upper limit are excluded at 95% CL. |
| Tables | |
png pdf |
Table 1:
Number of selected events, and the number of signal and background events expected from simulation in the leptonic analysis. The expectations for signal and background correspond to an integrated luminosity of 2.2 fb$^{-1}$. "Full selection'' refers to the additional requirements of $ {p_{\mathrm {T}}} ^{\mathrm{ t } }> $ 250 GeV and $ {p_{\mathrm {T}}} ^{j_1+j_2}> $ 350 GeV for both channels, and also 100 $ < m_{\mathrm{ t } } < $ 250 GeV in the muon channel, while ''Object selection'' omits these requirements. The quoted uncertainty does not include systematic uncertainties that affect the shape of distributions (a complete description of sources of uncertainty can be found in Section 6). |
png pdf |
Table 2:
Number of selected events, and the number of signal and background events expected from simulation in the hadronic analysis. The expectations for signal and background correspond to an integrated luminosity of 2.6 fb$^{-1}$. The quoted uncertainty does not include systematic uncertainties that affect the shape of distributions (a complete description of sources of uncertainty can be found in Section 6). |
png pdf |
Table 3:
Sources of systematic uncertainty affecting the $ {M_{\mathrm{ t } \mathrm{ b } }} $ distribution taken into account when setting 95% CL upper limits. The three right-most columns indicate the channels to which the uncertainty applies (noted by $\circ $), and whether it also applies to signals (noted by a check mark). When a source applies to both channels, it is treated as fully correlated in the combination. Sources that list the changes as $\pm $1 standard deviation (s.d.) depend on the distribution of the variable given in the parentheses, while those that list the variation as a percent are rate uncertainties. |
| Summary |
|
Searches have been reported for a heavy $\mathrm{W}_{R}'$ boson resonance decaying into a top and a bottom quark in data from proton-proton collisions at $\sqrt{s}= $ 13 TeV collected with the CMS detector. Analysis of the leptonic and hadronic channels is based on an integrated luminosity of 2.2 and 2.6 fb$^{-1}$, respectively. No evidence is observed for the production of a $\mathrm{W}_{R}'$ boson, and upper limits at 95% confidence level on $\sigma(\mathrm{ p }\mathrm{ p }\to\mathrm{W}_{R}')\,\mathcal{B}(\mathrm{W}_{R}'\to\mathrm{ t }\mathrm{ b })$ are determined as a function of the $\mathrm{W}_{R}'$ boson mass. After combining the two analyses, the upper limits at 95% confidence level are compared to the predicted $\mathrm{W}_{R}'$ boson production cross sections. $\mathrm{W}_{R}'$ bosons are excluded for masses less than 2.4 TeV if $M_{\mathrm{W}_{R}'}\gg M_{\nu_\mathrm{R}}$, and less than 2.6 TeV if $M_{\mathrm{W}_{R}'} |
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