Measurement of <i>J/ψ</i> production as a function of event activity in <i>p</i> + <i>p</i> collisions at √ <i>s</i> = 510 GeV with STAR at RHIC

We present measurements of J /ψ production in the dielectron channel at mid rapidity (| y | &lt;1) over the transverse momentum range 4 &lt; p T &lt; 12 GeV/ c examined as a function of the charged-particle multiplicity within |η| &lt; 1. Our measurements reveal a faster-than-linear increase in J /ψ production with respect to charged-particle multiplicity, extending previously reported trends at 200 GeV. The divergence of the trends for RHIC and LHC at higher multiplicity may constrain theoretical models incorporating multi-parton interactions and color-string percolation.