Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV

• Main Author: CMS collaboration (2265 authors)
• Publication Date: 2018
• Other Authors: Nayak, Aruna, Bargassa, Pedrame, Beirão Da Cruz E Silva, Cristóvão, Di Francesco, Agostino, Faccioli, Pietro, Galinhas, Bruno, Gallinaro, Michele, Hollar, Jonathan, Leonardo, Nuno, Lloret Iglesias, Lara, Seixas, Joao, Strong, Giles, Toldaiev, Oleksii, Vadruccio, Daniele, Varela, Joao, Vischia, Pietro, David Tinoco Mendes, Andre, Silva, Pedro, Musella, Pasquale
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://dx.doi.org/10.1088/1748-0221/13/05/P05011; http://hdl.handle.net/10400.26/27535

Many measurements and searches for physics beyond the standard model at the LHC rely on the efficient identification of heavy-flavour jets, i.e. jets originating from bottom or charm quarks. In this paper, the discriminating variables and the algorithms used for heavy-flavour jet identification during the first years of operation of the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, are presented. Heavy-flavour jet identification algorithms have been improved compared to those used previously at centre-of-mass energies of 7 and 8 TeV. For jets with transverse momenta in the range expected in simulated $\mathrm{t}\overline{\mathrm{t}}$ events, these new developments result in an efficiency of 68% for the correct identification of a b jet for a probability of 1% of misidentifying a light-flavour jet. The improvement in relative efficiency at this misidentification probability is about 15%, compared to previous CMS algorithms. In addition, for the first time algorithms have been developed to identify jets containing two b hadrons in Lorentz-boosted event topologies, as well as to tag c jets. The large data sample recorded in 2016 at a centre-of-mass energy of 13 TeV has also allowed the development of new methods to measure the efficiency and misidentification probability of heavy-flavour jet identification algorithms. The heavy-flavour jet identification efficiency is measured with a precision of a few per cent at moderate jet transverse momenta (between 30 and 300 GeV) and about 5% at the highest jet transverse momenta (between 500 and 1000 GeV).