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| CMS-PAS-B2G-17-010 | ||
| Search for heavy resonances decaying to a top and bottom quark in the lepton+jets final state in proton-proton collisions recorded by the CMS detector at 13 TeV | ||
| CMS Collaboration | ||
| March 2017 | ||
| Abstract: A search is presented for heavy gauge bosons decaying to a top and bottom quark using data collected by the CMS experiment at $\sqrt{s} =$ 13 TeV in 2016. The data set analyzed corresponds to an integrated luminosity of 35.9 fb$^{-1}$. Final states that include a single lepton (e,$\mu$), multiple jets, and missing transverse energy are analyzed. We find no evidence for the production of a W' boson, and are able to exclude at 95% confidence level the production of right-handed W' bosons with masses below 3.4 TeV if $ M_{ W'_{\mathrm{R}} } \gg M_{\nu_{\mathrm{R} } } $ and 3.6 TeV if $ M_{W'_{\mathrm{R}}} < M_{\nu_{\mathrm{R}}} $ at 95% confidence level. Exclusion limits for W' bosons are also presented as a function of their coupling strength to left- and right-handed fermions. The results presented are the most stringent limits published to date in the tb decay channel. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PLB 777 (2017) 39. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag (top) and 2 b-tag (bottom) categories, for the electron (left) and muon (right) channels, for Type A events. "LF" and "HF" 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 cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 1-a:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag category, for the electron channel, for Type A events. "LF" and "HF" 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 cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 1-b:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag category, for the muon channel, for Type A events. "LF" and "HF" 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 cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 1-c:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 2 b-tag category, for the electron channel, for Type A events. "LF" and "HF" 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 cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 1-d:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 2 b-tag category, for the muon channel, for Type A events. "LF" and "HF" 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 cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 2:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag (top) and 2 b-tag (bottom) categories, for the electron (left) and muon (right) channels, for Type B events. The simulated $ \mathrm{W}'_{\mathrm{R}} $ signal and background samples are normalized to the cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 2-a:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag category, for the electron channel, for Type B events. The simulated $ \mathrm{W}'_{\mathrm{R}} $ signal and background samples are normalized to the cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 2-b:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 1 b-tag category, for the muon channel, for Type B events. The simulated $ \mathrm{W}'_{\mathrm{R}} $ signal and background samples are normalized to the cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 2-c:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 2 b-tag category, for the electron channel, for Type B events. The simulated $ \mathrm{W}'_{\mathrm{R}} $ signal and background samples are normalized to the cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 2-d:
The reconstructed $ {M_{\mathrm {tb}}} $ distributions in the 2 b-tag category, for the muon channel, for Type B events. The simulated $ \mathrm{W}'_{\mathrm{R}} $ signal and background samples are normalized to the cross section and the luminosity of the data set used. The distribution is shown after the application of all selections. The 1$\sigma $ background uncertainty includes all uncertainties on the predicted background, while the $\sigma _\textrm {tot}$ is the combined uncertainty on the background and data. |
png pdf |
Figure 3:
95% C.L. upper limit on the W' boson production cross section separately in the electron (top) and muon (bottom) channels for right-handed W'. W' boson masses for which the theoretical cross section (in red and/or blue) exceeds the observed upper limit (in solid black) are excluded at 95% C.L. The green and yellow bands represent the $\pm $ 1 and 2 standard deviation uncertainties on the expected limit, respectively. |
png pdf |
Figure 3-a:
95% C.L. upper limit on the W' boson production cross section separately in the electron channel for right-handed W'. W' boson masses for which the theoretical cross section (in red and/or blue) exceeds the observed upper limit (in solid black) are excluded at 95% C.L. The green and yellow bands represent the $\pm $ 1 and 2 standard deviation uncertainties on the expected limit, respectively. |
png pdf |
Figure 3-b:
95% C.L. upper limit on the W' boson production cross section separately in the muon channel for right-handed W'. W' boson masses for which the theoretical cross section (in red and/or blue) exceeds the observed upper limit (in solid black) are excluded at 95% C.L. The green and yellow bands represent the $\pm $ 1 and 2 standard deviation uncertainties on the expected limit, respectively. |
png pdf |
Figure 4:
95% C.L. upper limit on the W' boson production cross section for right-handed W'. W' boson masses for which the theoretical cross section (in red and/or blue) exceeds the observed upper limit (in solid black) are excluded at 95% C.L. The green and yellow bands represent the $\pm $1 and 2 standard deviation uncertainties on the expected limit, respectively. |
png pdf |
Figure 5:
Expected (left) and observed (right) limits on the W' signal mass as function of the left-handed ($a_{\mathrm{L}}$) and right-handed ($a_{\mathrm{R}}$) couplings. Black lines represent contours of equal mass. |
png pdf |
Figure 5-a:
Expected limit on the W' signal mass as function of the left-handed ($a_{\mathrm{L}}$) and right-handed ($a_{\mathrm{R}}$) couplings. Black lines represent contours of equal mass. |
png pdf |
Figure 5-b:
Observed limit on the W' signal mass as function of the left-handed ($a_{\mathrm{L}}$) and right-handed ($a_{\mathrm{R}}$) couplings. Black lines represent contours of equal mass. |
| Tables | |
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Table 1:
Observed event yield and expected event yield from all background processes and three different signal masses. Yields are separated into 8 event categories by lepton type (e or $\mu $), number of b-tags (1 or 2), and $p_{\mathrm{T}}^{top}$ and $p_{\mathrm{T}}^{j_1+j_2}$ (Type A or Type B). The uncertainty on the total expected background includes both systematic and statistical sources. |
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Table 2:
List of systematic uncertainties taken into account in the analysis. For sources which affect the shape of the M(tb) distribution the rate uncertainty given is approximate. The Pileup, Top $ {p_{\mathrm {T}}} $ Reweighting, and W+jets Heavy/Light Flavor systematic uncertainties are described in more detail in the text. A checkmark in the "Signal" column indicates that the uncertainty is also applied to signal samples. (*)For signal samples only the shape component of the uncertainty due to parton distribution functions is included. |
| Summary |
|
We have performed a search for a heavy W' boson resonance decaying to a top and a bottom quark in lepton + jets final states in data collected at $\sqrt{s}=$ 13 TeV by the CMS detector in 2016. The integrated luminosity of the data set analyzed is 35.9 fb$^{-1}$. We observe no evidence for the production of a W' boson, and 95% upper limits on $\sigma(pp\rightarrow\textrm{W'}_{R})\times\mathcal{B}(\textrm{W'}_{R}\rightarrow\textrm{tb})$ are determined as a function of the $W'_{R}$ boson mass. The observed (expected) 95% confidence level upper limit is 3.4 (3.3) TeV if $M_{W'_{\mathrm{R}}}\gg M_{\nu_{\mathrm{R}}}$ and 3.6 (3.5) TeV if $M_{W'_{\mathrm{R}}} |
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Compact Muon Solenoid LHC, CERN |
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