Combination of cross-section measurements for associated production of a single top-quark and a W boson at √s = 8 TeV with the ATLAS and CMS experiments


A combination of cross-section measurements for the associated production of a top quark and a W boson in proton-proton collisions at √s = 8 TeV by the ATLAS and CMS experiments is presented. The two measurements are based on integrated luminosities of 20.3 fb−1 and 12.2 fb−1, respectively. The combined production cross section of a single top quark and a W boson is determined as σtW = 25.0 1.4 (stat.) 4.4 (syst.) 0.7 (lumi.) pb = 25.0 4.7 pb, in agreement with the NLO+NNLL expectation. A 95% C.L. lower limit on the magnitude of the CKM matrix element Vtb of |Vtb| > 0.79 is extracted from the cross- section measurement.

Input measurements

  • CMS (12.2 fb−1): Evidence for associated production of a single top quark and W Boson in pp collisions at √s=7 TeV, Phys. Rev. Lett. 110 (2013) 022003, arXiv:1209.3489.
  • ATLAS (20.3 fb−1): Measurement of the cross-section for associated production of a top quark and a W boson at √s = 8 TeV with the ATLAS detector, ATLAS-CONF-2013-100 (2013).

Public Document

CMS PAS TOP-14-009/ATLAS-CONF-2014-052:


The combined associated single-top production in association with a W boson cross section is σtW = 25.0 1.4 (stat.) 4.4 (syst.) 0.7 (lumi.) pb = 25.0 4.7 pb


Figure Caption
Cross-section measurements for the associated production of a top quark and a W boson per- formed by ATLAS and CMS, and combined result compared with the NLO+NNLL prediction [20] (gray bands). Statistical and total uncertainties are represented by red and blue error bars, respectively. The uncertainties in the theoretical prediction are represented by dark and light gray bands for renormalisa- tion/factorisation scale and PDF (evaluated using MSTW2008 [22]), respectively.


Table Caption
Categories of uncertainty, their magnitude (relative to the individual measurements) and corre- lation (ρ) between the ATLAS and CMS measurements. Uncertainties in the same row can be compared between experiments even if they have different names in the two analyses. The names here are the same as those in the original documents.
Contribution of each uncertainty category to the combined cross-section uncertainty.
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.

-- LucaLista - 29 Sep 2014

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PNGpng Table-1.png r1 manage 144.4 K 2014-09-29 - 10:58 LucaLista  
PNGpng Table-2.png r1 manage 33.7 K 2014-09-29 - 10:58 LucaLista  
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PDFpdf singletop_tW.pdf r2 r1 manage 35.1 K 2015-08-28 - 17:45 AndreasMeyer  
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