Evidence for Simultaneous Production of J /ψ and Mesons

We report evidence for the simultaneous production of J/ψ and mesons in 8.1 fb-1 of data collected at s=1.96 TeV by the D0 experiment at the Fermilab pp¯ 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(stat)±0.9(syst) mb.