Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV
Идентификация тяжёлых флейворных джетов с детектором CMS в pp-столкновениях при 13 ТэВ
2018-05-08
SCID: 54.1/m4yjmdrc
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b jet taggingboosted double-b taggingc jet taggingefficiency and misidentification measurementheavy-flavour jet identification
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Abstract (AI)
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).
Key Findings
1
CMS heavy-flavour jet identification algorithms for 13 TeV pp collisions are presented, including discriminating variables and algorithm descriptions.
2
For the first time, algorithms were developed to identify jets containing two b hadrons in Lorentz-boosted topologies and to tag c jets.
3
Large 2016 13 TeV data sample enabled new methods to measure identification efficiencies and misidentification probabilities with precision of a few percent (30–300 GeV) and ~5% (500–1000 GeV).
4
New algorithms achieve 68% b-jet identification efficiency at 1% light-jet misidentification probability for jets with pT typical of simulated tt̄ events.
5
Relative b-jet identification efficiency improved by about 15% at 1% misidentification probability compared to 7 and 8 TeV CMS algorithms.
Research Object
Heavy-flavour jets reconstructed by the CMS detector in proton–proton (pp) collisions at sqrt(s) = 13 TeV
Research Subject
Identification performance and algorithms for tagging heavy-flavour jets (b and c jets, including double-b in boosted topologies): discriminating variables, tagging efficiencies, misidentification probabilities, and measurement methods across jet pT ranges
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2018-05-08
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