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PHENIX Study on J/ψ Production: Results and Insights

Explore the physics motivation, measurement techniques, and J/ψ production results in various collision scenarios. Gain insights into initial state effects, baseline measurements, and suppression mechanisms. Discussion on understanding J/ψ suppression in Au+Au collisions using different models.

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PHENIX Study on J/ψ Production: Results and Insights

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  1. Study J/y Production in PHENIX • Content: • Physics Motivation • How PHENIX measure J/ψ • PHENIX results on J/ψ production • Summary and discussion W. Xie (Riken-BNL Research Center) for PHENIX Collaboration 22nd Winter Workshop, La Jolla

  2. 4 K+ e-/- e-/- e+/+ J/y K- e+/+ l D0 l Physics Motivation • Initial state effect: • Gluon (anti-)shadowing • Nuclear absorption. • Initial state energy loss. • Cronin effect • Hot/dense medium effect • Color screening • charm recombination • bound state • Final state nuclear effect • Comover scattering • backward reaction 22nd Winter Workshop, La Jolla

  3. How PHENIX Measure J/ψ Good electron identification from Ring Imaging Cherenkov detector (RICH) and Electromagnetic Calorimeter (EMCal). • high resolution tracking and momentum measurement from Drift chamber. High rate capability: powerful level-1 electron trigger Good momentum resolution and muon identification from mID and mTrk. High rate capability: powerful level-1 dimuon trigger 22nd Winter Workshop, La Jolla

  4. What has been Measured so far for J/ψ Production • at s = 200 GeV p-p collisions in RUN2(150nb-1) and RUN3 (350nb-1) • Run2 results published at PRL 92, 051802(2004) • at s = 200 GeV d-Au collisions at RUN3 (2.74nb-1) • With p-p results, published at PRL 96, 012304 (2006) • at s = 200 GeV Au-Au collisions in RUN2 (24µb-1),Run4 (241µb-1) • QM2005 • at s = 200 GeV Cu-Cu collisions in RUN5 (3nb-1) and s = 62 GeV Cu-Cu collisions Run5 (0.19nb-1) • QM2005 22nd Winter Workshop, La Jolla

  5. J/Psi Baseline Measurement The total cross section in p-p collisions is: 2.61+/-0.20(fit)+/-0.26(abs) µb 22nd Winter Workshop, La Jolla

  6. rapidity y X2 X1 J/ in South y < 0 Anti Shadowing Shadowing X1 X2 J/ in North y > 0 J/Psi Baseline Measurement South (y < -1.2) : • large X2 (in gold) ~ 0.090 Central (y ~ 0) : • intermediate X2 ~ 0.020 North (y > 1.2) : • small X2 (in gold) ~ 0.003 gluons in Pb / gluons in p X 22nd Winter Workshop, La Jolla Eskola, et al., Nucl. Phys. A696 (2001) 729-746.

  7. J/Psi Baseline Measurement • No xbj scaling expected for shadowing effect. • Parents gluon loose energy via hadronization before the hard scattering to form ccbar pairs. • Energy loss is weaker and shadowing becomes stronger with increasing s since the ccbar coherence length increase with energy (B. Kopeliovich et al., Nuclear Physics A696 (2001) 669-714) The xF scaling behavior in low collision energy could be • an coincidence of convoluted effect for shadowing, energy loss and nuclear absorption ? • Sudakov effect ? (hep-ph/0501260) 22nd Winter Workshop, La Jolla

  8. J/Psi Baseline Measurement Low x2 ~ 0.003 (shadowing region) 0 mb 3 mb 0 mb 5 mb • Weaker shadowing and absorption • stronger suppression in more central collision • favor σABS ~ 1-3 mb comparing to the σABS ~ 4.18  0.35 mb from NA50 • more luminosity is need to further constrain the cold nuclear effect. 22nd Winter Workshop, La Jolla

  9. Understanding J/ suppression in Au+Au Collisions • cold nuclear effect • shadowing • absorption • …etc Stronger suppression in central collision than the poorly constrained cold nuclear effect. 22nd Winter Workshop, La Jolla

  10. Digal, Fortunato, Satz hep-ph/0310354 Capella, Sousa EPJ C30, 117 (2003) Capella, Ferreiro hep-ph/0505032 QGP screening comovers Understanding J/ suppression in Au+Au Collisions • color screening, comover • model discribe the NA50 results well • But over predict the suppression at RHIC 22nd Winter Workshop, La Jolla

  11. Understanding J/ suppression in Au+Au Collisions • Feed-down from melted c and y’ 22nd Winter Workshop, La Jolla

  12. Understanding J/ suppression in Au+Au Collisions • Regeneration • statistical hadronization. • In-medium formation. Agree with the data except in the most central collisions Kostyuk (hep-ph/0305277) • Andronic (nucl-th/0303036) Grandchamp, Rapp, Brown hep-ph/0306077 Thews, hep-ph/0504266 22nd Winter Workshop, La Jolla

  13. Understanding J/ suppression in Au+Au Collisions • J/Psi transport: • Zhu (nucl-th/0411093) • Bratkovskaya (nucl-th/0402042) Kostyuk Andronic Rapp Bratkovskaya Zhu 22nd Winter Workshop, La Jolla

  14. Comparison with other observables • suppression can not distinguish models by itself. • Need multi-dimensional comparison to understand the production mechnism. • recombination model predict • narrower of pT and rapidity distribution due to the recombination. • It would be important to see similar prediction from other models. 22nd Winter Workshop, La Jolla

  15. 22 normal Cronin pT broadening mixture All regeneration Comparison with other observables • Extraction of <pT2> by fittingwith A(1+(pT/B)2)-6 • Data agree with recombination model prediction. 22nd Winter Workshop, La Jolla

  16. Comparison with other observables • prediction of rapidity distribution from cold nuclear effect. • rapidity shape from pure in-medium formation is too narrow to describe the data. • Need more realistic calculation. 22nd Winter Workshop, La Jolla

  17. The Results will be improved by Run5 p+p Collisions • large error bars for R_AA come from the low statistics of run3 p+p results. • a factor of 10 more luminosity in run5 p+p collision • Results coming very soon South muon arm Central arm north muon arm 22nd Winter Workshop, La Jolla

  18. A Bright Future 22nd Winter Workshop, La Jolla

  19. Backup slides 22nd Winter Workshop, La Jolla

  20. 22nd Winter Workshop, La Jolla

  21. 23 Rapidity dependence • Au+Au and Cu+Cu (200GeV) Cu+Cu (200GeV) No significant change in rapidity shape in Au+Au and Cu+Cu. RAA is flat as a function of rapidity, which is not predicted by the recombination model. 22nd Winter Workshop, La Jolla

  22. Phenix muon arm 1st Upsilons at RHIC ! poster: Production in √s = 200 GeV p + p Collisions at PHENIX in 2005 S. Butsyk, M.Leitch for PHENIX Collaboration We Have a Lot More Data from p-p Collisions in RUN5! PHENIX accumulated ~3pb-1 p-p collision during 2005 run. 22nd Winter Workshop, La Jolla

  23. Rapidity What’s the Cold Nuclear Effect in Au-Au Collsions Nuclear suppression can be obtained directly from d-Au collisions. • Need more data to have an accurate baseline measurement • One of the major uncertainty comes from limited statistics in run3 p-p collisions. 22nd Winter Workshop, La Jolla

  24. 22nd Winter Workshop, La Jolla

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