Measurement of relative J/psi yield versus charged-particle multiplicity in p+p collisions at sqrt(s)=200 GeV with the STAR experiment
We report the latest results of relative J/psi yield versus charged-particle multiplicity at mid-rapidity in p+p collisions at sqrt(s)=200 GeV with the STAR experiment. The measured J/psi yields and charged-particle multiplicities have been corrected for STAR detector acceptance and efficiency, and are compared to results from LHC experiments as well as theoretical calculations based on phenomenological models or event generators. It is found that the STAR data exhibit a faster-than-linear increase of J/psi yield versus charged-particle multiplicity, suggesting not only correlation between soft and hard interactions, but also stronger suppression on soft interactions than hard interactions or stronger enhancement to hard interactions than soft interactions in high multiplicity p+p collisions. Such a behavior is found to be independent of beam collisional energies when comparing the STAR results at sqrt(s)=200 GeV with the LHC results at sqrt(s)=7 TeV. The faster-than-linear increase is underestimated by the PYTHIA8 event generator including multiple parton interactions. The observed global trend independent of beam collisional energy is consistent with the Percolation model predication, but not with predications by the EPOS3 event generator with hydrodynamic evolution.