Observation and measurements of the production of prompt and non-prompt $J/\psi$ mesons in association with a $Z$ boson in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

Abstract

The production of a $Z$ boson in association with a $J/\psi$ meson in proton-proton collisions probes the production mechanisms of quarkonium and heavy flavour in association with vector bosons, and allows studies of multiple parton scattering. Using $20.3\mathrm{f}{\mathrm{b}}^{-1}$ of data collected with the ATLAS experiment at the LHC in $pp$ collisions at $\sqrt{s}=8\mathrm{TeV}$, the first measurement of associated $Z+J/\psi$ production is presented for both prompt and non-prompt $J/\psi$ production, with both signatures having a significance in excess of $5\sigma$. The inclusive production cross-sections for $Z$ boson production (analysed in ${\mu }^{+}{\mu }^{-}$ or $e^{+}{e}^{-}$ decay modes) in association with prompt and non-prompt $J/\psi (\to {\mu }^{+}{\mu }^{-})$ are measured relative to the inclusive production rate of $Z$ bosons in the same fiducial volume to be $(36.8\pm 6.7\pm 2.5)\times 10^{-7}$ and $(65.8\pm 9.2\pm 4.2)\times 10^{-7}$ respectively. Normalised differential production cross-section ratios are also determined as a function of the $J/\psi$ transverse momentum. The fraction of signal events arising from single and double parton scattering is estimated, and a lower limit of $5.3(3.7)\mathrm{mb}$ at $68(95)$% confidence level is placed on the effective cross-section regulating double parton interactions.

Published version, 15 pages + author list + cover page (30 pages total), 6 figures, 5 tables, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2014-01/

References in corpus (15)

• PYTHIA 6.4 Physics and Manual
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• New parton distributions for collider physics
• Event generation with SHERPA 1.1
• Heavy quarkonium: progress, puzzles, and opportunities
• FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order
• Electron and photon energy calibration with the ATLAS detector using LHC Run 1 data
• Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton-proton collision data
• J/psi (psi') production at the Tevatron and LHC at O(α_s^4v^4) in nonrelativistic QCD
• On the mechanisms of heavy-quarkonium hadroproduction
• Conventional versus single-ladder-splitting contributions to double parton scattering production of two quarkonia, two Higgs bosons and $c\bar{c}c\bar{c}$
• The $h\to 4\ell$ spectrum at low $m_{34}$: Standard Model vs. light New Physics
• Electroweak boson production in double parton scattering
• A note on Higgs decays into $Z$ boson and $J/\Psi ({\rm Y})$
• Probing New Physics in Higgs Couplings to Fermions using an Angular Analysis

Cited by in corpus (8)

• Measurement of the prompt $J/\psi$ pair production cross-section in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
• Study of hard double-parton scattering in four-jet events in $pp$ collisions at $\sqrt{s}=7$ TeV with the ATLAS experiment
• Associated production of a quarkonium and a Z boson at one loop in a quark-hadron-duality approach
• Double parton scattering in pair-production of $J/\psi$ mesons at the LHC revisited
• Phenomenological analysis of associated production of $Z^0+b$ in the $b\to J/\psi X$ decay channel at the LHC
• Studies of inclusive four-jet production with two b-tagged jets in proton-proton collisions at 7 TeV
• Double quarkonium production at high Feynman-$x$
• Z-dark search with the ATLAS detector