/ hep-ex CMS-SMP-15-009

Measurement of associated Z + charm production in proton-proton collisions at $\sqrt{s} =$ 8 TeV

Abstract: 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 $p_{\rm T}^{\ell} >$ 20 GeV, ${|\eta^{\ell}|} <$ 2.1, 71 $< m_{\ell\ell} <$ 111 GeV, and heavy flavour jets with $p_{\rm T}^{{\rm jet}} >$ 25 GeV and ${|\eta^{{\rm jet}}|} <$ 2.5. The Z + c production cross section is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X}) {\cal B}(\mathrm{Z} \rightarrow \ell^+\ell^-) =$ 8.8 $\pm$ 0.5 (stat) $\pm$ 0.6 (syst) pb. The ratio of the Z + c and Z + b production cross sections is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X})/\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{b} + \mathrm{X}) =$ 2.0 $\pm$ 0.2 (stat) $\pm$ 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.

Note: *Temporary entry*; Submitted to Eur. Phys. J. C. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/SMP-15-009/ (CMS Public Pages)

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Запись создана 2017-12-04, последняя модификация 2017-12-04

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