Combination of single top-quark cross-section measurements in the t-channel at √s=8 TeV with the ATLAS and CMS experiments


A combination of measurements of the single top-quark production cross-section in the t-channel at √s=8 TeV by the ATLAS and CMS experiments at the LHC is presented. The measurements from ATLAS and CMS are based on integrated luminosities of 5.8 fb-1 and 5.0 fb-1, respectively. The best linear unbiased estimator (BLUE) method is applied for the combination, taking into account the individual contributions to systematic uncertainties of the two experiments and their correlations. The combined single top-quark production cross-section in the t-channel is σt-ch.=85 ± 4 (stat.) ± 11 (syst.) ± 3 (lumi.) pb = 85 ±12 pb.11 which is in agreement with the theoretical predictions.


Figure Caption
Figure 1 Single top-quark production cross-section measurements performed by ATLAS and CMS, and combined result (light-blue band), compared with SM predictions (pink bands). Statistical, systematic and luminosity uncertainties are represented by blue error bars, ordered from the innermost to the outermost. For theoretical predictions the renormalisation/factorisation scale uncertainty and PDF uncertainty are represented by red error bars, ordered from the innermost to the outermost.
Theoretical predictions are taken from Phys. Rev. Lett. 102 (2009) 182003 (top) and arXiv:1205.3453 (bottom).


Table Caption
Table 1 Categories of sources of uncertainties for the ATLAS and CMS measurements with assumed correlation factors (ρ) The relative cross-section uncertainty corresponding to each source of uncertainty is shown for both measurements. The total uncertainty, shown for each measurement, is the quadratic sum of all individual uncertainties.
Table 2 Contribution of each uncertainty category to the combined cross-section uncertainty.
Table 3 Results of the stability tests performed on the correlation assumptions about the uncertainty categories. For each test the correlation factor ρ is varied from its default value to a test value and the corresponding shifts on the combined central value and on the measured uncertainty are reported.

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Topic revision: r2 - 2014-03-26 - AndreasMeyer
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