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| CMS-PAS-TOP-15-012 | ||
| Combinations of the CMS alternative technique measurements of the top quark mass | ||
| CMS Collaboration | ||
| November 2016 | ||
| Abstract: A new combination of the CMS top quark mass measurements is presented. The combination uses the measurements that were not included in the published CMS Run I result. The measurements use alternative analysis techniques, and the combination is used to cross check the published result for $m_{\rm t}$. The combination gives a result of $m_{\rm t} =$ 172.58 $\pm$ 0.21 (stat) $\pm$ 0.72 (syst) GeV with a precision of 0.4%, which is in very good agreement with the published CMS Run I combination. While slightly less precise, this study provides an independent verification of the published result. It also provides some pointers towards possible improvements with the data from Run II. When combined with the published measurements, a result of 172.43 $\pm$ 0.13 (stat) $\pm$ 0.46 (syst) GeV for $m_{\rm t}$ is obtained. This is essentially the same as the published value, indicating that the new results are strongly correlated with the published measurements, and/or have not yet reached the precision needed to improve the published result. | ||
| Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Summary of the new CMS mass measurements and the results derived from their combination. |
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Figure 2:
Summary of the combinations presented in this report. |
| Tables | |
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Table 1:
CMS measurements of $m_{\rm t}$ that were not included in the Run 1 legacy analysis. The measurements and their statistical and total systematic uncertainties are expressed in GeV. |
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Table 2:
Nominal correlation coefficients for the systematic uncertainties. The term $\rho _{\rm chan}$ is the correlation factor for measurements in the same top quark decay channel, but different years and the term $\rho _{\rm year}$ is the correlation between measurements in different channels from the same year. |
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Table 3:
Statistical correlation coefficients for the CMS measurements not included in the published Run I analysis. |
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Table 4:
Combination coefficients for the full non-legacy combination. |
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Table 5:
Correlations between input measurements. |
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Table 6:
Combination coefficients for the measurements without significant overlap in technique. |
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Table 7:
Combination coefficients for the measurements considered to be using alternative mass fitting techniques. |
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Table 8:
Combination coefficients for the 8 TeV measurements considered to be using alternative mass fitting techniques. |
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Table 9:
Category breakdown of systematic uncertainties for the combined mass results. The uncertainties are expressed in GeV. The first column corresponds to the legacy measurement, the second to combination III, and the last to the combination of the new and legacy measurements (combination V). The n/a entries for the entries for secondary vertex mass and single top modeling indicate that these were not applicable for this combination (see Sec. 3). |
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Table 10:
Combination coefficients for the seven legacy measurements and the eight non-legacy measurements from Sec. 5.2. |
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Table 11:
Correlations between input measurements. |
| Summary |
| In this report we have presented a new combination of the CMS top quark mass measurements. This uses measurements that were not included in the published CMS Run I analysis and which were designed to marginalize the sensitivity to the jet energy scale uncertainties. The new analyses also do not require the full reconstruction of the $\mathrm{ t \bar{t} }$ final state to determine the value of $m_{\rm t}$. Thus the combination of these new measurements provides an important cross check of the published result. The mass derived from these alternative analyses is |
| References | ||||
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