# 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 $20.3$ fb$^{-1}$ of data collected with the ATLAS experiment at the LHC, in $pp$ collisions at $\sqrt{s}=8$ 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 (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 $(88\pm 16\pm 6) \times 10^{-8}$ and $(157\pm 22\pm 10) \times 10^{-8}$ respectively. Normalised differential production cross-sections 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 $5.3\ (3.7)$ mb at $68\ (95)$% confidence level is placed on the effective cross-section regulating double parton interactions.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-01097769
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Submitted on : Monday, December 22, 2014 - 8:54:49 AM
Last modification on : Tuesday, April 13, 2021 - 3:35:15 AM

### Citation

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. 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. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2015, 75 (5), pp.229. ⟨10.1140/epjc/s10052-015-3406-9⟩. ⟨in2p3-01097769⟩

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