Measurement of the tt̄ production cross-section using eμ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

• Autores: Alconada Verzini, María Josefina; Alonso, Francisco; Arduh, Francisco Anuar; Dova, María Teresa; Monticelli, Fernando Gabriel; Wahlberg, Hernán Pablo; The ATLAS Collaboration
• Año de publicación: 2016
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Física; measurement; proton-proton collisions; ATLAS detector
• Institución: Universidad Nacional de La Plata

This paper describes a measurement of the inclusive top quark pair production cross-section (σtt̄ ) with a √ data sample of 3.2 fb−1 of proton–proton collisions at a centre-of-mass energy of s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously σtt̄ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt̄ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented.
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Instituto de Física La Plata
Facultad de Ciencias Exactas