Measurements of b-jet tagging efficiency with the ATLAS detector using $ t\overline{t} $ events at $ \sqrt{s}=13 $ TeV

• Autor(a) principal: ATLAS collaboration (2913 authors)
• Data de Publicação: 2018
• Outros Autores: Aguilar Saavedra, Juan Antonio, Amor Dos Santos, Susana Patricia, Araque Espinosa, Juan Pedro, Castro, Nuno Filipe, Conde Muino, Patricia, Da Cunha Sargedas De Sousa, Mario Jose, Dias DO Vale, Tiago, Faisca Rodrigues Pereira, Rui Miguel, Fiolhais, Miguel, Galhardo, Bruno, Gomes, Agostinho, Goncalo, Ricardo, Jorge, Pedro, Machado Miguens, Joana, Maio, Amelia, Maneira, Jose, Mendes Gouveia, Emanuel Demetrio, Oleiro Seabra, Luis Filipe, Onofre, Antonio, Costa Batalha Pedro, Rute, Pereira Peixoto, Ana Paula, Santos, Helena, Saraiva, Joao, Silva, Jose Manuel, Tavares Delgado, Ademar, Veloso, Filipe, Wolters, Helmut
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.26/27626

The efficiency to identify jets containing b-hadrons (b-jets) is measured using a high purity sample of dileptonic top quark-antiquark pairs ( $ t\overline{t} $ ) 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 $ \sqrt{s}=13 $ TeV. Two methods are used to extract the efficiency from $ t\overline{t} $ 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.