1. 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

2. Outline 02/23/2013 Alexandre Lebedev (ISU)2

3. Introduction 02/23/2013 Alexandre Lebedev (ISU)3 …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, quarkonium states, p T and rapidity dependence…

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

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

6. J/  at Low(er) Energies 02/23/2013 Alexandre Lebedev (ISU)6 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. A.Adare et. al., Phys. Rev. C 86, 064901 (2012)

7. One Possible Explanation 02/23/2013 Alexandre Lebedev (ISU)7 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!

8. Asymmetric Collisions (Cu+Au) 02/23/2013 Alexandre Lebedev (ISU)8 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).

9. Lots of New Results in d+Au Collisions 02/23/2013 Alexandre Lebedev (ISU)9 J/  as a function of centrality, rapidity and p T (new)  ’ at mid-rapidity as a function of centrality (new)  C at mid-rapidity (new)

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

11. J/  R dAu Centrality Dependence 02/23/2013 Alexandre Lebedev (ISU)11 Integrated over p T J/  are suppressed at all centralities and rapidities. Shadowing plus nuclear breakup reproduces well minimum bias results (not shown), but not rapidity and centrality 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

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

13.  C in d+Au 02/23/2013 Alexandre Lebedev (ISU)13 Charmonium R dAu seems to depend on binding energy. Better  C measurement is needed though.

14. Conclusions 02/23/2013 Alexandre Lebedev (ISU)14 J/  R AA is similar at 200, 62, and 39 GeV. In Cu+Au J/  suppression is stronger in Cu-going direction. P T dependence of J/  R dAu at negative (Au-going) rapidity is different from mid and positive rapidity. J/  R dAu centrality dependence is “non-linear” at positive (d-going) rapidity. Large suppression of  ’ in central d+Au collisions.

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

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

17. J/  R dAu Minimum Bias 02/23/2013 Alexandre Lebedev (ISU)17

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

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

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