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Latest Charmonium Results from the PHENIX Experiment at RHIC

Latest Charmonium Results from the PHENIX Experiment at RHIC. Alexandre Lebedev ( Iowa State University) For the PHENIX Collaboration. Lake Louise Winter Institute - February 23, 2013. Outline. J/ y in Au+Au collisions at = 39 and 62 GeV

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Latest Charmonium Results from the PHENIX Experiment at RHIC

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  1. Latest Charmonium Results from the PHENIX Experiment at RHIC AlexandreLebedev(Iowa State University) For the PHENIX Collaboration Lake Louise Winter Institute - February 23, 2013

  2. Outline J/y in Au+Au collisions at = 39 and 62 GeV J/y in Cu+Au collisions at = 200 GeV J/y in d+Au collisions vspT, rapidity, and centrality y’ and cC in d+Au collisions 02/23/2013 Alexandre Lebedev (ISU)

  3. Introduction …color screening will prevent cc binding in the deconfined region. - Matsui and Satz, 1986 Charmonium is an excellent tool for measuring screening length and temperature in QGP… … but only if we know all our references. Many competing processes in AA collisions: color screening, initial state effects, regeneration, cold nuclear matter effects, feed-down… … need measurements for different energies, colliding species, quarkoniumstates, pT and rapidity dependence… 02/23/2013 Alexandre Lebedev (ISU)

  4. Nuclear Modification Factor RAA Yield in nucleus-nucleus collisions divided by p+p yields and scaled by the appropriate number of binary collisions NCOLL, which is calculated using Glaubermodel. Centrality of collision is described by number of participant nucleons NPART Impact parameter [fm] 02/23/2013 Alexandre Lebedev (ISU)

  5. The PHENIX Experiment Charmonium states are measured via di-lepton decays Central Arms (electrons) |h| < 0.35 Df = 2 × p/2 P > 0.2 GeV Muon Arms 1.2 < |h| < 2.2 Df = 2p P > 2 GeV 02/23/2013 Alexandre Lebedev (ISU)

  6. J/y at Low(er) Energies A.Adare et. al., Phys. Rev. C 86, 064901 (2012) Surprisingly, similar suppression is observed at 200, 62 and 39 GeV No PHENIX baseline in p+p at 39 and 62GeV, use extrapolations from CERN and Fermilab experiments. 02/23/2013 Alexandre Lebedev (ISU)

  7. One Possible Explanation Regeneration compensates for suppression in QGP. Calculations by X. Zhao and R. Rapp, Phys. Rev. C 82, 064905 (2010) But cold nuclear matter effects should be different! 02/23/2013 Alexandre Lebedev (ISU)

  8. Asymmetric Collisions (Cu+Au) Suppression in Au-going direction same as in AuAu and CuCu, But stronger in Cu-going direction. Partially explained by CNM (shadowing and nuclear breakup). 02/23/2013 Alexandre Lebedev (ISU)

  9. Lots of New Results in d+Au Collisions J/y as a function of centrality, rapidity and pT (new) y’ at mid-rapidity as a function of centrality (new) cC at mid-rapidity (new) 02/23/2013 Alexandre Lebedev (ISU)

  10. J/yRdAuvspT Phys. Rev. D 86, 092006 (2012) Minimum bias results. Similar suppression at mid-rapidity and forward (d-going) rapidity. Suppression below ≈ 4 GeV. RdAu ≈ 1 above 4 GeV. Different RdAupT dependence at forward (Au-going) rapidity. Enhancement above ≈ 1 GeV. No clear explanation from theory for the forward result. 02/23/2013 Alexandre Lebedev (ISU)

  11. J/yRdAu Centrality Dependence Integrated over pT J/y are suppressed at all centralities and rapidities. Shadowing plus nuclear breakup reproduces well minimum bias results (not shown), but not rapidity andcentrality dependence together. Centrality dependence at forward rapidity (Au-going direction) implies non-linear dependence on nuclear thickness. Forward rapidity described well by CGC Impact parameter is poorly defined in d+Au Phys. Rev. Lett. 107 (2011) 142301 02/23/2013 Alexandre Lebedev (ISU)

  12. y’ in d+Au Stronger suppression for y’ than for J/y in most central collisions. 02/23/2013 Alexandre Lebedev (ISU)

  13. cCin d+Au CharmoniumRdAu seems to depend on bindingenergy. Better cC measurement is needed though. 02/23/2013 Alexandre Lebedev (ISU)

  14. Conclusions J/y RAA is similar at 200, 62, and 39 GeV. In Cu+Au J/y suppression is stronger in Cu-going direction. PT dependence of J/yRdAu at negative (Au-going) rapidity is different from mid and positive rapidity. J/yRdAu centrality dependence is “non-linear” at positive (d-going) rapidity. Large suppression of y’ in central d+Au collisions. 02/23/2013 Alexandre Lebedev (ISU)

  15. Backup Slides 02/23/2013 Alexandre Lebedev (ISU)

  16. CNM in Cu+Au 02/23/2013 Alexandre Lebedev (ISU)

  17. J/yRdAu Minimum Bias 02/23/2013 Alexandre Lebedev (ISU)

  18. y’ RdAu Comparison to Lower Energies If charmonium formation time is shorter than the time spent Traversing the nucleus, larger suppression will be observed. Does not hold at RHIC energy! 02/23/2013 Alexandre Lebedev (ISU)

  19. J/y Flow 02/23/2013 Alexandre Lebedev (ISU)

  20. J/yTransverse Single Spin Asymmetry 02/23/2013 Alexandre Lebedev (ISU)

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