Measurements of b-jet tagging efficiency with the ATLAS detector using tt ¯ events at √s =13 TeV

Abraham, N L, Allbrooke, B M M, Asquith, L, Cerri, A, Chavez Barajas, C A, De Santo, A, Jones, S D, Lerner, G, Miano, F, Salvatore, F, Santoyo Castillo, I, Shaw, K, Stevenson, T J, Suruliz, K, Sutton, Mark, Tresoldi, F, Trovato, F, Vivarelli, I, Winkels, E, Winston, O J, The ATLAS Collaboration, and others, (2018) Measurements of b-jet tagging efficiency with the ATLAS detector using tt ¯ events at √s =13 TeV. Journal of High Energy Physics, 2018 (89). pp. 1-46. ISSN 1126-6708

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The efficiency to identify jets containing b -hadrons (b -jets) is measured using a high purity sample of dileptonic top quark-antiquark pairs (tt ¯ ) selected from the 36.1 fb −1 of data collected by the ATLAS detector in 2015 and 2016 from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy s √ =13 TeV. Two methods are used to extract the efficiency from tt ¯ events, a combinatorial likelihood approach and a tag-and-probe method. A boosted decision tree, not using b -tagging information, is used to select events in which two b -jets are present, which reduces the dominant uncertainty in the modelling of the flavour of the jets. The efficiency is extracted for jets in a transverse momentum range from 20 to 300 GeV, with data-to-simulation scale factors calculated by comparing the efficiency measured using collision data to that predicted by the simulation. The two methods give compatible results, and achieve a similar level of precision, measuring data-to-simulation scale factors close to unity with uncertainties ranging from 2% to 12% depending on the jet transverse momentum.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Experimental Particle Physics Research Group
Subjects: Q Science > QC Physics
Depositing User: Alice Jackson
Date Deposited: 19 Nov 2018 12:24
Last Modified: 19 Nov 2018 12:25

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