Study of multiplicity-dependent charmonia production in p+p collisions at PHENIX Jongho Oh and Sanghoon Lim for the PHENIX collaboration Motivation PHENIX muon spectroscopy Charmonia measurement Results Multiplicity-dependent 𝐽/𝜓production Comparison with other results ‣ Forward Silicon Vertex Tracker - 4 stations of silicon strip detector - precise measurement of the radial direction of track trajectory at forward rapidity - charged particle multiplicity ‣ Muon Tracker - 3 stations of cathode strip chamber - momentum measurements of charged tracks ‣ Muon Identifier - 5 layers of 2 planes of Iraocci tube chambers and steel absorber - hadron/muon separation PHENIX muon arms are composed of Forward Silicon Vertex Tracker, Muon Tracker, and Muon Identifiers to measure hadron/muon tracks at forward rapidity region • At least one MuTr-FVTX matching is required to separate 𝐽/𝜓and 𝜓(2𝑆) • Signal shape: Crystal ball function and 2nd Gaussian function • Combinatorial background: Mixed events normalized with like-sign • Correlated background: Modified Hagedorn function based on the measurements of correlated dimuons Phys. Rev. D 99, 072003 (2019) • 𝐽/𝜓and multiplicity at mid-rapidity èA similar multiplicity dependence is observed in 200 GeV and 13 TeV Tracks from 𝐽/𝜓are included in both results, but more significant impact in 200 GeV due to smaller multiplicity (𝑑𝑁!"/𝑑𝜂in 13 TeV is about x3 larger than 200 GeV) • PHENIX results without subtraction of muons from 𝐽/𝜓 èA similar multiplicity dependence with the LHC results • After the subtraction of muons from 𝐽/𝜓 èSignificantly lower multiplicity dependence than STAR results (same collision energy without subtraction) ALICE results (higher collision energy without subtraction) • At 200 GeV where 𝑑𝑁!"/𝑑𝜂is comparable with 2 (tracks from 𝐽/𝜓), considering the muon contribution is very important to interpret the multiplicity dependence • Multiparton interaction is important for 𝐽/𝜓production for both energies collective behavior arXiv:1906.09928 South arm −2.2 < 𝜂< −1.2 North arm 1.2 < 𝜂< 2.4 Phys. Rev. C 105, 065912 (2022) Phys. Lett. B 810 (2020) 135758 Phys. Lett. B 786 (2018) 87 • 𝐽/𝜓at forward rapidity and multiplicity at mid-rapidity èIncreasing yield as charged particle multiplicity becomes larger • 𝐽/𝜓at forward rapidity and multiplicity at backward rapidity èA similar trend in the results with the multiplicity at mid-rapidity • 𝐽/𝜓and multiplicity at the same rapidity (forward rapidity) Multiplicity without subtraction of muons from 𝐽/𝜓 èMore steeply increasing than other results Multiplicity with subtraction of muons from 𝐽/𝜓 èWeaker multiplicity-dependence and similar trend with other results • Comparison with PYTHIA8 A better agreement with the Detroit tune for RHIC energies than the Monash tune Monash Tune Detroit Tune Phys. Rev. D 105, 016011 (2022) Outlook • Multiplicity-dependent 𝐽/𝜓and 𝜓(2𝑆) ratio is ongoing to study final-state effects in p+p collisions • Two PYTHIA tunes show different multiplicity dependence in the 𝐽/𝜓and 𝜓(2𝑆) ratio èAnother check of the underlying event description • Inclusive 𝐽/𝜓yield increases with particle multiplicity in p+p collisions at 13 TeV and 200 GeV èSimilar multiplicity dependence at two energies èMultiparton interaction is important for 𝐽/𝜓production in both energies 𝐽/𝜓and charged particle multiplicity at mid-rapidity èCharged tracks of the decay product are included in the charged particle multiplicity èMultiplicity dependence is possibly affected depending on 𝑑𝑁!"/𝑑𝜂values • In PHENIX, multiplicity can be measured in various regions èDetailed correlation between 𝐽/𝜓production and underlying events can be investigated Phys. Rev. C 95, 034904 (2017) • Relative suppression of 𝜓(2𝑆) than 𝐽/𝜓 becomes stronger as the multiplicity density increases in p/3He+A collisions èFinal-state effects • The study can be extended even in p+p collisions èThe system size is small but almost independent of the multiplicity