Observation and measurements of the production of prompt and non-prompt ... formula ... mesons in association with a ... formula ... boson in ... formula ... collisions at ... formula ... with the ATLAS detector

摘要

The production of a Z boson in association with a J/ψ 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 s=8TeV, the first measurement of associated Z +  J/ψ production is presented for both prompt and non-prompt J/ψ production, with both signatures having a significance in excess of 5σ. The inclusive production cross-sections for Z boson production (analysed in μ⁺μ^- or e⁺e^- decay modes) in association with prompt and non-prompt J/ψ( → μ⁺μ^-) are measured relative to the inclusive production rate of Z bosons in the same fiducial volume to be (36.8 ± 6.7 ± 2.5)  ×  10^-7 and (65.8 ± 9.2 ± 4.2)  ×  10^-7 respectively. Normalised differential production cross-section ratios are also determined as a function of the Jψ transverse momentum. The fraction of signal events arising from single and double parton scattering is estimated, and a lower limit of id="IEq25">5.3 (3.7) mb at id="IEq26">68 (95)% confidence level is placed on the effective cross-section regulating double parton interactions.