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

The associated production of vector boson with heavy quarkonia is a key observable for understanding the quarkonium production mechanisms. In this poster the first evidence of the production of the $Z$ boson in association with a prompt and non-prompt $J/\psi$ meson is presented and its production rate is measured in comparison of the inclusive $Z$ production. Relative contributions to the signal from single and double parton scattering are estimated. Single parton scattering cross-sections are compared to cutting-edge theoretical calculations in the colour singlet and colour octet formalisms. Finally, a lower limit in the double parton scattering effective cross section is extracted.