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| CMS-EXO-22-006 ; CERN-EP-2025-191 | ||
| Search for a new neutral gauge boson produced in association with one or two b jets and decaying into a pair of muons in proton-proton collisions at $ \sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| 14 November 2025 | ||
| Submitted to J. High Energy Phys. | ||
| Abstract: A search for a new neutral gauge boson, Z', produced in association with one or two jets, including at least one b jet, and decaying into a pair of muons is presented. The analysis uses proton-proton collision data collected with the CMS detector at $ \sqrt{s} = $ 13 TeV, corresponding to an integrated luminosity of 138 fb$ ^{-1} $. No significant deviation from background expectations is observed. Upper limits at 95% confidence level on the product of cross section, branching fraction to dimuons, acceptance, and efficiency, from 0.2 to 2 fb, are set for Z' boson masses between 125 and 350 GeV. Process-dependent products of acceptance and efficiency, and model-independent limits on the signal yield are provided. These are the only results to date in the 125-200 GeV mass range and the most stringent for b quark fusion production modes in the 200-350 GeV range, complementing inclusive Z' boson searches. | ||
| Links: e-print arXiv:2511.11853 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Representative Feynman diagrams of Z' boson production with bottom-bottom or bottom-strange quark fusion with decays into a dimuon final state. Production at tree level (left), single associated initial-state radiation (ISR) jet production (middle), and two associated ISR jet production (right) are shown. |
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Figure 1-a:
Representative Feynman diagrams of Z' boson production with bottom-bottom or bottom-strange quark fusion with decays into a dimuon final state. Production at tree level (left), single associated initial-state radiation (ISR) jet production (middle), and two associated ISR jet production (right) are shown. |
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Figure 1-b:
Representative Feynman diagrams of Z' boson production with bottom-bottom or bottom-strange quark fusion with decays into a dimuon final state. Production at tree level (left), single associated initial-state radiation (ISR) jet production (middle), and two associated ISR jet production (right) are shown. |
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Figure 1-c:
Representative Feynman diagrams of Z' boson production with bottom-bottom or bottom-strange quark fusion with decays into a dimuon final state. Production at tree level (left), single associated initial-state radiation (ISR) jet production (middle), and two associated ISR jet production (right) are shown. |
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Figure 2:
Distributions of the search-specific variables from simulated backgrounds and signals for Z' boson masses of 125, 200, and 350 GeV after object selections including a single-muon requirement and categorization into both jet multiplicities. The left column shows the $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ distributions, and the right column shows the $ p_{\mathrm{T}}^\text{miss}/m_{\ell\ell} $ distributions. The upper row shows the 1-jet category distributions, and the lower row shows the 2-jet category distributions. Overflow events are not shown. |
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Figure 2-a:
Distributions of the search-specific variables from simulated backgrounds and signals for Z' boson masses of 125, 200, and 350 GeV after object selections including a single-muon requirement and categorization into both jet multiplicities. The left column shows the $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ distributions, and the right column shows the $ p_{\mathrm{T}}^\text{miss}/m_{\ell\ell} $ distributions. The upper row shows the 1-jet category distributions, and the lower row shows the 2-jet category distributions. Overflow events are not shown. |
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Figure 2-b:
Distributions of the search-specific variables from simulated backgrounds and signals for Z' boson masses of 125, 200, and 350 GeV after object selections including a single-muon requirement and categorization into both jet multiplicities. The left column shows the $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ distributions, and the right column shows the $ p_{\mathrm{T}}^\text{miss}/m_{\ell\ell} $ distributions. The upper row shows the 1-jet category distributions, and the lower row shows the 2-jet category distributions. Overflow events are not shown. |
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Figure 2-c:
Distributions of the search-specific variables from simulated backgrounds and signals for Z' boson masses of 125, 200, and 350 GeV after object selections including a single-muon requirement and categorization into both jet multiplicities. The left column shows the $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ distributions, and the right column shows the $ p_{\mathrm{T}}^\text{miss}/m_{\ell\ell} $ distributions. The upper row shows the 1-jet category distributions, and the lower row shows the 2-jet category distributions. Overflow events are not shown. |
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Figure 2-d:
Distributions of the search-specific variables from simulated backgrounds and signals for Z' boson masses of 125, 200, and 350 GeV after object selections including a single-muon requirement and categorization into both jet multiplicities. The left column shows the $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ distributions, and the right column shows the $ p_{\mathrm{T}}^\text{miss}/m_{\ell\ell} $ distributions. The upper row shows the 1-jet category distributions, and the lower row shows the 2-jet category distributions. Overflow events are not shown. |
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Figure 3:
A visualization of the ABCD SRs and CRs. For example, $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ represents the dimuon b jet enriched SRs ($ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ or $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $) and $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $ represents the dielectron b jet enriched CRs ($ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $ or $ \mathrm{CR}_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mathrm{e}\mathrm{e}} $). |
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Figure 4:
Comparison between the predictions of the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background from simulation (gray) and the ABCD method (teal) from MC simulation. Events are divided by the bin width. The statistical and systematic uncertainties using the ABCD method are shown around it in a teal hashed area. The ratio of the nominal MC background values (dashed line) to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. Left: $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Right: $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. |
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Figure 4-a:
Comparison between the predictions of the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background from simulation (gray) and the ABCD method (teal) from MC simulation. Events are divided by the bin width. The statistical and systematic uncertainties using the ABCD method are shown around it in a teal hashed area. The ratio of the nominal MC background values (dashed line) to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. Left: $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Right: $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. |
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Figure 4-b:
Comparison between the predictions of the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background from simulation (gray) and the ABCD method (teal) from MC simulation. Events are divided by the bin width. The statistical and systematic uncertainties using the ABCD method are shown around it in a teal hashed area. The ratio of the nominal MC background values (dashed line) to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. Left: $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Right: $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. |
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Figure 5:
The 1-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between data and simulation in $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 5-a:
The 1-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between data and simulation in $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 5-b:
The 1-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between data and simulation in $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 5-c:
The 1-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between data and simulation in $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 6:
The 2-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between the MC and data in $ \mathrm{CR}_{\text{2j}}^{\mu\mu} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 6-a:
The 2-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between the MC and data in $ \mathrm{CR}_{\text{2j}}^{\mu\mu} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 6-b:
The 2-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between the MC and data in $ \mathrm{CR}_{\text{2j}}^{\mu\mu} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 6-c:
The 2-jet CRs with data fits used for the $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ background prediction. Upper left: $ \mathrm{CR_{\text{j}}^{\mu\mu}} $. Upper right: $ \mathrm{CR_{\mathrm{b}}^{\mathrm{e}\mathrm{e}}} $. Lower: $ \mathrm{CR_{\text{j}}^{\mathrm{e}\mathrm{e}}} $. Events are divided by the bin width. We observe a shape difference between the MC and data in $ \mathrm{CR}_{\text{2j}}^{\mu\mu} $. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background is included as a comparison, and is not used for predictions. |
png pdf |
Figure 7:
Distributions of $ m_{\ell\ell} $ in the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ (left) and $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ (right) SRs. Events are divided by the bin width. Simulated signal shapes for Z' boson masses of 125, 200, and 350 GeV are shown. The "Stat + syst" band shows the envelope of the fit variations with statistical uncertainties. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. |
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Figure 7-a:
Distributions of $ m_{\ell\ell} $ in the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ (left) and $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ (right) SRs. Events are divided by the bin width. Simulated signal shapes for Z' boson masses of 125, 200, and 350 GeV are shown. The "Stat + syst" band shows the envelope of the fit variations with statistical uncertainties. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. |
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Figure 7-b:
Distributions of $ m_{\ell\ell} $ in the $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $ (left) and $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $ (right) SRs. Events are divided by the bin width. Simulated signal shapes for Z' boson masses of 125, 200, and 350 GeV are shown. The "Stat + syst" band shows the envelope of the fit variations with statistical uncertainties. The ratio of the nominal MC background values (dashed line) and data to the ABCD prediction is shown as a dashed line in the ratio plot. The MC background uncertainties are not shown for visual clarity. |
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Figure 8:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
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Figure 8-a:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
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Figure 8-b:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
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Figure 8-c:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
png pdf |
Figure 9:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
png pdf |
Figure 9-a:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
png pdf |
Figure 9-b:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
png pdf |
Figure 9-c:
Data (black) vs. the ABCD method background prediction (blue) for 2016 (left), 2017 (middle), and 2018 (right) data-taking years in $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. Events are divided by the bin width. Error bars show statistical uncertainties of data. The blue band shows the propagated uncertainty of all individual fit variations in a given bin, which we consider to be uncorrelated. The lower panels show the ratio of the observed data to the background estimation. |
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Figure 10:
The asymptotic 95% CL limits on the product of cross section($ \sigma $), branching fraction into a pair of muons ($ \mathcal{B} $) to dimuons, acceptance (A), and efficiency ($ \epsilon $). Left is $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $, right is $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. A combination of both limits depends on the relative acceptance contributions in each region and is omitted here. |
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Figure 10-a:
The asymptotic 95% CL limits on the product of cross section($ \sigma $), branching fraction into a pair of muons ($ \mathcal{B} $) to dimuons, acceptance (A), and efficiency ($ \epsilon $). Left is $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $, right is $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. A combination of both limits depends on the relative acceptance contributions in each region and is omitted here. |
png pdf |
Figure 10-b:
The asymptotic 95% CL limits on the product of cross section($ \sigma $), branching fraction into a pair of muons ($ \mathcal{B} $) to dimuons, acceptance (A), and efficiency ($ \epsilon $). Left is $ \mathrm{SR_{\mathrm{b}}^{\mu\mu}} $, right is $ \mathrm{SR_{\mathrm{b}+\text{j}/\mathrm{b}}^{\mu\mu}} $. A combination of both limits depends on the relative acceptance contributions in each region and is omitted here. |
| Tables | |
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Table 1:
Summary of object selection requirements on leptons, veto leptons, and jets passing and failing b jet identification. All objects have a maximum $ |\eta| $ of 2.4. The efficiencies of the respective identification working points are detailed in the text of Section 2. |
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Table 2:
Number of jet requirements for the SRs and CRs based on opposite-sign dilepton pair flavor, number of b-tagged jets ($ N_{\mathrm{b}} $), and the overall number of jets ($ N^{\text{all}}_{\text{jets}} $). Events with more than two leptons passing veto lepton selections of any flavor are discarded. In the chosen benchmark model, the Z' boson does not decay into electrons, hence the use of the dielectron CRs. |
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Table 3:
Summary of additional $ m_{\ell\ell} $-dependent event selection requirements on $ p_{\mathrm{T}}^\text{miss} $ and $ H_{\mathrm{T}}{-}L_{\mathrm{T}} $ BQF variables to suppress backgrounds. The jet multiplicity column indicates the maximum value the BQF variables can have to pass the selection for the respective number of jets. |
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Table 4:
Overview of systematic uncertainty sources and their ranges. Systematic uncertainties that are treated as fully or partially correlated across the data-taking years are labeled with an asterisk. |
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Table 5:
Acceptance times efficiency by the SR for events with no generator-level matrix element ISR jets of strange or bottom flavor. Exactly one bottom quark contributes directly to the Z' boson production vertex. Statistical and systematic uncertainties for this 0b(1b) category are listed. |
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Table 6:
Acceptance times efficiency by the SR for events with no generator-level matrix element ISR jets of strange or bottom flavor. Exactly two bottom quarks contribute directly to the Z' boson production vertex. Statistical and systematic uncertainties for this 0b(2b) category are listed. |
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Table 7:
Acceptance times efficiency by the SR for events with exactly one generator-level matrix element ISR jets of bottom flavor. Statistical and systematic uncertainties for this 1b category are listed. |
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Table 8:
Acceptance times efficiency by the SR for events with exactly one generator-level matrix element ISR jets of strange flavor. Statistical and systematic uncertainties for this 1s category are listed. |
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Table 9:
Acceptance times efficiency by the SR for events with exactly two generator-level matrix element ISR jets, one of which has strange, the other bottom flavor. Statistical and systematic uncertainties for this 1b+1s category are listed. |
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Table 10:
Acceptance times efficiency by the SR for events with exactly two generator-level matrix element ISR jets of bottom flavor. Statistical and systematic uncertainties for this 2b category are listed. |
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Table 11:
Acceptance times efficiency by the SR for events with exactly two generator-level matrix element ISR jets of strange flavor. Statistical and systematic uncertainties for this 2s category are listed. |
| Summary |
| A search for a new neutral Z' gauge boson with nonuniversal couplings, decaying into a pair of muons and produced with one or two associated jets, where at least one is b tagged, has been presented. The analysis is based on LHC proton-proton collision data at $ \sqrt{s} = $ 13 TeV, collected by the CMS experiment during 2016-2018, corresponding to an integrated luminosity of 138 fb$ ^{-1} $. Exclusion bounds prior to this analysis predominantly focused on Z' boson production with universal couplings through light-quark fusion, leading to less stringent constraints on this signature. This analysis provides a complementary approach by targeting Z' boson production through bottom quark fusion, improving the sensitivity to this less-constrained region. The presented results set the first specific limits on the product of cross section, branching fraction to dimuons, acceptance, and efficiency for bZ' and bjZ' production with Z' decays into a pair of muons. The data are consistent with the background-only hypothesis, showing no evidence of a signal. Limits at 95% confidence level on the product of cross section, branching fraction to dimuons, acceptance, and efficiency, ranging from 0.2 to 2 fb, are set for Z' boson masses between 125 and 350 GeV. Process-dependent products of acceptance and efficiency, and model-independent limits on the signal yield are provided. These limits are presently the only results in the mass range of 125-200 GeV. In the mass range of 200-350 GeV, these results provide the most stringent constraints on the specified set of bottom quark fusion production modes, serving as a complementary approach to inclusive Z' boson searches. |
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