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

The collaboration
Eur.Phys.J.C 75 (2015) 229, 2015.

Abstract (data abstract)
CERN-LHC. 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 $20.3\, \mathrm{fb^{-1}}$ 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.

• #### Table 1

Data from Section 6

10.17182/hepdata.73284.v1/t1

The fiducial, inclusive (SPS+DPS) and DPS-subtracted differential cross-section ratio $R_{Z+J/\psi}$ for prompt $J/\psi$.

• #### Table 2

Data from Section 6

10.17182/hepdata.73284.v1/t2

The fiducial, inclusive (SPS+DPS) and DPS-subtracted differential cross-section ratio $R_{Z+J/\psi}$ for non-prompt $J/\psi$.

• #### Table 3

Data from Table 4

10.17182/hepdata.73284.v1/t3

The fiducial, inclusive (SPS+DPS) and DPS-subtracted differential cross-section ratio $\mathrm{d}R_{Z+J/\psi}/\mathrm{d}y$ as a function of $y_{J/\psi}$ for prompt $J/\psi$.

• #### Table 4

Data from Table 4

10.17182/hepdata.73284.v1/t4

The fiducial, inclusive (SPS+DPS) and DPS-subtracted differential cross-section ratio $\mathrm{d}R_{Z+J/\psi}/\mathrm{d}y$ as a function of $y_{J/\psi}$ for non-prompt $J/\psi$.

• #### Table 5

Data from Table 5

10.17182/hepdata.73284.v1/t5

The inclusive (SPS+DPS) cross-section ratio $\mathrm{d}R_{Z+J/\psi}^\mathrm{incl}/\mathrm{d}p_\mathrm{T}$ for prompt and non-prompt $J/\psi$. Estimated DPS contributions for each bin, based on the...

• #### Table 6

Data from Table 5

10.17182/hepdata.73284.v1/t6

The inclusive (SPS+DPS) cross-section ratio $\mathrm{d}R_{Z+J/\psi}^\mathrm{incl}/\mathrm{d}p_\mathrm{T}$ for prompt and non-prompt $J/\psi$. Estimated DPS contributions for each bin, based on the...