Evidence for the associated production of a W boson and a top quark in ATLAS at sqrt{s}=7 TeV

0388969 - FZÚ 2013 RIV NL eng J - Journal Article
Aad, G. - Abbott, B. - Abdallah, J. - Böhm, Jan - Chudoba, Jiří - Gallus, Petr - Gunther, Jaroslav - Hruška, I. - Juránek, Vojtěch - Kepka, Oldřich - Kupčo, Alexander - Kůs, Vlastimil - Lokajíček, Miloš - Marčišovský, Michal - Mikeštíková, Marcela - Myška, Miroslav - Němeček, Stanislav - Růžička, Pavel - Schovancová, Jaroslava - Šícho, Petr - Staroba, Pavel - Svatoš, Michal - Taševský, Marek - Tic, Tomáš - Valenta, J. - Vrba, Václav - Zeman, Martin … Total 2868 authors
Evidence for the associated production of a W boson and a top quark in ATLAS at sqrt{s}=7 TeV.
Physics Letters. B. Roč. 716, č. 1 (2012), s. 142-159. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA MŠMT LA08032
Institutional research plan: CEZ:AV0Z10100502
Keywords : ATLAS * LHC * top quark * W+t * single top-quark * W hadronproduction * CKM matrix
Subject RIV: BF - Elementary Particles and High Energy Physics
Impact factor: 4.569, year: 2012
http://arxiv.org/abs/arXiv:1205.5764

This letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb^-1 of pp collision data at sqrt(s) = 7 TeV accumulated with the ATLAS detector at the LHC. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothesis at the 3.3 sigma level, the expected sensitivity assuming the Standard Model production rate being 3.4 sigma. The corresponding cross-section is determined and found to be sigma_Wt = 16.8 +/- 2.9 (stat) +/- 4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element |V_{tb}| = 1.03{+0.16}{-0.19} is derived assuming that the Wt production through |V_{ts}| and |V_{td}| is small.
Permanent Link: http://hdl.handle.net/11104/0217887