Speaker
Description
$J/\psi$, a charmonium bound state made of a charm and an anti-charm quark, has been discovered in the 1970s and confirmed the quark model. Because the mass of charms quarks is significantly above the QCD scale, charmonia are considered as excellent probes to test pQCD calculations. Over the past decades, they have been studied extensively at different high-energy colliders. However, their production mechanisms, which involves in multiple scales, are still not very well understood. Recently, in high multiplicity $p+p$ collisions at RHIC and at the LHC, a significant enhancement of $J/\psi$ production yield has been observed, which suggests a strong contribution from the Multi-Parton Interaction (MPI). This is different from the traditional pQCD picture where charm quark pairs are produced from a single hard scattering between partons in $p + p$ collisions. In this talk, we will report the $J/\psi$ normalized production yield as a function of normalized charged particle multiplicity over a board range of rapidity and event multiplicity in the $J/\psi \to \mu^+ \mu^-$ channel with PHENIX Run 16 $p+p$ data at $\sqrt s =200$ GeV as a function of event multiplicity. The result is compared with PYTHIA 8 simulation with the MPI on and off. In addition, the status of this analysis using $p + Au$ and $Au + p$ collisions will be presented and discussed along with Color Glass Condensate (CGC) predictions. Finally, the status of multiplicity dependent $\psi(2S)/J/\psi$ ratio analysis in $p + p$ data will be presented along with a discussion on its sensitivity to charmonium bound state.
| What kind of work does this abstract pertain to? | Experimental |
|---|---|
| Which experiment is this abstract related to? | PHENIX |
