Measurement of associated Z + charm production in proton-proton collisions at sqrt(s) = 8 TeVстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 17 апреля 2018 г.
Аннотация:A study of the associated production of a Z boson and a charm quark jet (Z + c), and a comparison to production with a b quark jet (Z + b), in pp collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb−1, collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with pℓT> 20 GeV, |ηℓ|< 2.1, 71 <mℓℓ< 111 GeV, and heavy flavour jets with pjetT> 25 GeV and |ηjet|< 2.5. The Z + c production cross section is measured to be σ(pp→Z+c+X)B(Z→ℓ+ℓ−)= 8.8 ± 0.5 (stat) ± 0.6 (syst) pb. The ratio of the Z + c and Z + b production cross sections is measured to be σ(pp→Z+c+X)/σ(pp→Z+b+X)= 2.0 ± 0.2 (stat) ± 0.2 (syst). The Z + c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.