We report evidence for the simultaneous production of J/ψ and Υ mesons in 8.1 fb−1 of data collected at s=1.96 TeV by the D0 experiment at the Fermilab ppˉ Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σeff=2.2±0.7\mbox(stat)±0.9\mbox(syst)\mboxmb.
@article{arxiv.1511.02428,
title = {Evidence for simultaneous production of $J/\psi$ and $\Upsilon$ mesons},
author = {D0 Collaboration},
journal= {arXiv preprint arXiv:1511.02428},
year = {2016}
}