Publication: Identification of heavy-flavor jets with the CMS detector in pp collisions at 13 TeV

About

Many measurements and searches for physics beyond the standard model at the LHC rely on the efficient identification of heavy-flavor jets, ie jets originating from bottom or charm quarks. In this paper, the discriminating variables and the algorithms used for heavy-flavor jet identification during the first years of operation of the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, are presented. Heavy-flavor jet identification algorithms have been improved compared to those used previously at center-of-mass energies of 7 and 8 TeV. For jets with transverse momenta in the range expected in simulated events, these new developments result in an efficiency of 68% for the correct identification of ab jet for a probability of 1% of misidentifying a light-flavor 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 center-of-mass energy of 13 TeV has also allowed the development of new methods to measure the efficiency and misidentification probability of heavy-flavor jet identification algorithms. The b 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).