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Understanding J/ Ψ Suppression Cold Nuclear Matter (CNM) extrapolations from p(d)+A to A+A

Understanding J/ Ψ Suppression Cold Nuclear Matter (CNM) extrapolations from p(d)+A to A+A. Present (PPG078) CNM Constraints on A+A data. R AA.

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Understanding J/ Ψ Suppression Cold Nuclear Matter (CNM) extrapolations from p(d)+A to A+A

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  1. Understanding J/Ψ Suppression Cold Nuclear Matter (CNM) extrapolations from p(d)+A to A+A Mike Leitch

  2. Present (PPG078) CNM Constraints on A+A data RAA CNM effects (EKS shadowing + dissociation from fits to d+Au data, with R. Vogt calculations) give large fraction of observed Au+Au suppression, especially at mid-rapidity PRC 77,024912(2008) & Erratum: arXiv:0903.4845 Au+Au mid-rapidity small-x (shadowing region) EKS shadowing band RAA RdAu d+Au Au+Au forward-rapidity more accurate d+Au constraint soon from 2008 data Mike Leitch

  3. New 2008 d+Au J/Ψ data - RCP • Initial d+Au J/Ψ update from new 2008 data (~30x 2003) • RCP pretty flat vs centrality at backward rapidity; but falls at forward rapidity (small-x) • more soon – precision statistics requires precision systematics & careful analysis EKS σ = 0,1,2,3,4,…15 Mike Leitch

  4. New CNM fits using 2008 PHENIX d+Au Rcp • similar to before, use models with shadowing & absorption/breakup • but allow effective breakup cross section to vary with rapidity • to obtain good description of data for projections to A+A • get “breakup(y)”; compare to E866/NuSea & HERA-B • Lourenco, Vogt, Woehri - arXiv:0901.3054 • common trend, with large increasing effective breakup cross section at large positive rapidity • need additional physics in CNM model – e.g. initial-state dE/dx with EKS shadowing with NDSG shadowing Mike Leitch

  5. Cross Check - Comparision of New Effective Breakup Cross Section fits to published 2003 d+Au RdAu Results • Fairly consistent with RdAu from old 2003 data • PRC 77,024912(2008) Mike Leitch

  6. Survival Probability after dividing out CNM “extrapolation” Results are shown as a function of a the multiplicity of charged particles (~ energy density, assuming SPS~RHIC) The relation between the charged multiplicity and NPart is obtained AuAu  using PHOBOS data (Phys.Rev.C65 061901 (2002) PbPb using NA50 data (Phys.Lett.B 530 1-4 (2002) 43-55) Good agreement between PbPb and AuAu Mike Leitch

  7. Comparison with new RHIC results Measured/Expected SPS results are compared with AuAu RHIC RAA results normalized to RAA(CNM) • Both Pb-Pb and Au-Au seem to depart from the reference curve at NPart~200 • For central collisions more important suppression in Au-Au with respect to Pb-Pb Mike Leitch

  8. Open Charm Nuclear Dependence from FNAL-E789/E866 Mike Leitch

  9. D0 -> K K-+ K+- Mass (GeV/c2) Fermilab E789: D0 & B  J/ψ X(charm & beauty using silicon) upstream downstream Dimuon spectrometer + B  J/ψ + X 16-plane, 50m pitch/8.5k strip silicon vertex detector Mike Leitch

  10. E866/NuSea Open Charm Measurement target  beam dump  2.34 m • hadronic cocktail explains ~30% of target & <5% of dump ’s • as expected since dump absorbs light hadrons before they can decay • charm decays consistent between Cu target and Cu dump • use same method for Be to get nuclear dependence Dump Target charm~ 20 hadrons charm~ 3.3 hadrons • data • hadrons • charm • E866/NuSea 800 GeV p+A • S. Klinksiek thesis - hep-ex_0609002 • paper in preparation Mike Leitch

  11. Rapidity dependence of open charm • Open-charm p+A nuclear dependence (single- pT > 1 GeV/c) – very similar to that of J/Ψ • dominant effects are in the initial state • e.g. shadowing, dE/dx, Cronin • weaker open-charm suppression at y=0 attributed to lack of absorption for open charm E866/NuSea 800 GeV p+A Mike Leitch

  12. Mike Leitch

  13. Mike Leitch

  14. PHENIX A+A Data and Features • PHENIX Au+Au data shows suppression at mid-rapidity about the same as seen at the SPS at lower energy • but stronger suppression at forward rapidity. • Forward/Mid RAA ratio looks flat above a centrality with Npart = 100 • Several scenarios may contribute: • Cold nuclear matter (CNM) effects • important, need better constraint • Sequential suppression • QGP screening only of C & ’- removing their feed-down contribution to J/ at both SPS & RHIC • Regeneration models • give enhancement that compensates for screening Centrality (Npart) Mike Leitch

  15. Looking for the cold nuclear matter baseline for J/ψ production at RHIC Tony Frawley Florida State University ECT, Trento May 26, 2009

  16. Many thanks for contributions/help from: Ramona Vogt Mike Leitch Alex Linden Levy Jamie Nagle Darren McGlinchey Tony Frawley, FSU

  17. The quarkonium plan SpeciesPurpose p+p Quarkonium production mechanisms Baseline cross sections for heavy ions d+Au Cold nuclear matter effects Baseline CNM RAA for heavy ions Cu+Cu Hot nuclear matter effects near TC Au+Au Hot nuclear matter effects well above TC Tony Frawley, FSU

  18. The PHENIX Detector J/ψ→e+e- -0.35 < y < 0.35 J/ψ→μ+μ- 1.2 < |y| < 2.2 Tony Frawley, FSU

  19. Brief review of the relevant J/ψ data Au+Au RAA Run 4 Au+Au + Run 5 p+p Cu+Cu RAA Run 5 Cu+Cu + Run 5 p+p d+Au RCP Run 8 d+Au To come: Run 8 RdAu with Run 6 pp reference Tony Frawley, FSU

  20. Reference data – Run 5 p+p PHENIX, PRL98, 2002 (2007) This is the reference data set for all nuclear modification factors shown here. Tony Frawley, FSU

  21. Cu+Cu and Au+Au RAA Phys. Rev. Lett. 101, 122301 (2008) The Npart dependence of Au+Au and Cu+Cu is consistent. Note the smaller systematic uncertainties for the Cu+Cu data. This is primarily due to smaller uncertainties on Ncoll from the Glauber calculation. Thus the Cu+Cu data will be much better for studying the onset of hot nuclear matter effects. Tony Frawley, FSU

  22. Au+Au RAA PHENIX – reference here The stronger Au+Au suppression at forward/backward rapidity has generated considerable interest. But what is the expected suppression due to cold nuclear matter effects? Tony Frawley, FSU

  23. d+Au RCP The first results for d+Au from Run 8, shown at QM09. Four centrality bins to make three RCP points: Tony Frawley, FSU

  24. What can we learn from the existing charmonium RAA data? • The heavy ion charmonium data alone have not taught us as much as we would like, because of serious uncertainties caused by: • 1) Poorly known initial state effects at RHIC: • Break up cross section for collisions with nucleons. • Shadowing. • Other effects? Initial state energy loss? • 2) Poorly known open charm production cross sections. • Thus the trade-off between coalescence and destruction is difficult to illuminate experimentally. • To try to make inroads on 1), we start from the most recent d+Au data set: • – Run 8 d+Au • First we briefly review previous attempts to use Run 3 d+Au data for this. Tony Frawley, FSU

  25. Au+Au mid-rapidity EKS shadowing band RAA Au+Au forward-rapidity Estimating the CNM RAA from Run 3 d+Au data - 1 This has been done before in three ways: 1) PHENIX (Phys. Rev. C 77, 024912 (2008) and erratum arXiv:0903.4845) fitted Run 3 RdAu using a single σbreakup at all rapidities + EKS98/nDSg shadowing calculations by Ramona Vogt. The CNM RAA was estimated using calculations of RAA for Cu+Cu and Au+Au by Ramona, using the fitted σbreakup + EKS98/nDSg. However (Phys. Rev. Lett. 101, 122301 (2008)PPG071), when a single σbreakup is used at all rapidities the ratio of the predicted y=0 to |y|=1.7 CNM RAA values is just a prediction of the shadowing model. Therefore this is not a good way to use the RdAu data to test if the increased suppression at |y|=1.7 is due to CNM effects. RAA Tony Frawley, FSU

  26. Estimating the CNM RAA from Run 3 d+Au data - 2 2) Raphael Granier de Cassagnac (J. Phys. G34, S955 (2007)) used direct folding of the RdAu data, with some assumptions, to predict the CNM RAA for Au+Au. This works only for Au+Au, since RdAu is used directly. This approach produces completely independent CNM RAA values at y=0 and |y|=1.7 – which is very good. But because of the low statistical precision of the Run 3 d+Au data, the results are inconclusive. This approach cannot be used with d+Au RCP data, nor can it be used to estimate a CNM RAA baseline for Cu+Cu. Tony Frawley, FSU

  27. Estimating the CNM RAA from Run 3 d+Au data - 3 3) The PHENIX RdAu data were fitted separately at y=0 and |y|=1.7 with σbreakup + EKS98/nDSg calculations by Ramona. The CNM RAA was predicted for Cu+Cu and Au+Au independently at y=0 and |y|=1.7 using calculations by Ramona. While this makes the ratio of the estimated CNM RAA at y=0 and |y|=1.7 sensitive to the RdAu data, it still assumes the forward and backward rapidity data have the same σbreakup. We will see this is not justified. NOTE: The uncertainty bands here are underestimated due to the fitting error that was corrected for 1). Not fixed here yet! Phys. Rev. Lett. 101, 122301 (2008) Tony Frawley, FSU

  28. Fitting the Run 8 d+Au RCP • We want to parameterize the d+Au RCP data so that we can predict the heavy ion RAA that would result from p+A physics only. • Fit RCP vs centrality independently at each rapidity using calculations of RdAu vs impact parameter by Ramona Vogt that include: • σbreakup for collisions of (forming) J/ψ with nucleons (0-15 mb, 1 mb steps). • A shadowing model – EKS98 and nDSg are used here. • Convert RdAu vs impact parameter to RdAu vs centrality using PHENIX Glauber impact parameter distribution for each dAu centrality bin. • Fit procedure: • Fit RCP vs centrality using only uncertainties that are uncorrelated in rapidity. • Vary RCP by +/- 1σ in uncertainties that are correlated in rapidity, and refit. • Vary RCP by +/- 1σ in uncertainties that are global with rapidity and refit. • Uncertainties are shown respectively as bars, boxes, and a global number. Tony Frawley, FSU

  29. Fits to d+Au RCP – example for EKS98 Integrated for each muon arm Tony Frawley, FSU

  30. σbreakup vs y from d+Au RCP fits with EKS98 and nDSg Tony Frawley, FSU

  31. Comparison with lower energy data – EKS98 fits Lourenco, Vogt and Woehri (JHEP 02 (2009) 014) published the effective breakup cross section vs y from fits to E866 and HERA-B data. Our results from 200 GeV are shown here compared with their results for the EKS98 case. For y > 1.2 the 200 GeV data follow the trend observed at lower energy remarkably closely! Tony Frawley, FSU

  32. Comparison with lower energy data – nDSG fits Note that the effective breakup cross section is significantly lower for y < 1.2. But for y > 1.2 there is little difference from the EKS case. Tony Frawley, FSU

  33. Sanity check! Comparision of new effective breakup cross section fits from RCP to published 2003 d+Au RdAu results • From the talk by Mike Leitch. • Fairly consistent with centrality integrated RdAu from old 2003 data • PRC 77,024912(2008) Tony Frawley, FSU

  34. Parameterize d+Au RCP at |y|= 0, 1.7 – EKS98 Integrated for each muon arm Tony Frawley, FSU

  35. Effective σbreakup used in Glauber calculations |y| = 0, 1.7 Tony Frawley, FSU

  36. Cold Nuclear Matter RAA for heavy ions Having “calibrated” the Vogt calculations at each rapidity, we estimate the CNM RAA using the results from the dAu RCP fits. To do this, we use a Glauber calculation for Au+Au that reproduces well the average Npart and Ncoll values for the centrality bins used by PHENIX. In the Glauber calculation: Each nuclear collision is placed in a centrality bin according to Npart. For each nucleon-nucleon collision: Determine impact parameter b1 of nucleon 1 in its target nucleus. Determine impact parameter b2 of nucleon 2 in its target nucleus. Add to the accumulated RAA: RdAu(b1,y=0) * RdAu(b2,y=0) Add to the accumulated RAA: RdAu(b1,y=-1.75) * RdAu(b2,y=1.75) After processing all events, print out at y=0 and y=1.7 forcentrality bin j: Nevts[j], Σ(RAA[j])/Nevts[j], Σ(Ncoll[j])/Nevts[j], Σ(Npart[j])/Nevts[j] Tony Frawley, FSU

  37. Estimation of uncertainties The CNM RAA is calculated for the central fitted σbreakup and for +/- 1σ in the type A (uncorrelated in rapidity) uncertainty and for +/- 1σ in the type B (correlated in rapidity) uncertainty. The type A uncertainty is shown as a vertical bar, and the type B as a box. Tony Frawley, FSU

  38. Heavy ion CNM baseline RAA – EKS98 parameterization Tony Frawley, FSU

  39. Heavy ion CNM baseline RAA – nDSg parameterization Tony Frawley, FSU

  40. Calculating the heavy ion RAA “survival probability” Now we can calculate the ratio RAA/RAA(CNM) from the measured RAA and the estimated RAA(CNM) shown on the previous slides. In the following plots the uncertainty in RAA/RAA(CNM) due to the uncorrelated (mostly statistical) uncertainty in the measured RAA is shown as a bar, the correlated uncertainty in the measured RAA us shown as a narrow box, and the uncertainty due to the estimated CNM RAA is shown as a wider box. Tony Frawley, FSU

  41. Heavy ion “survival probability” at y=0 (EKS example) Tony Frawley, FSU

  42. Heavy ion “survival probability” at |y| = 1.7 (EKS example) Tony Frawley, FSU

  43. Heavy ion “survival probability” - EKS98 parameterization Tony Frawley, FSU

  44. Heavy ion “survival probability” - nDSg parameterization Tony Frawley, FSU

  45. Comments We are just starting to try to understand the d+Au data and their implications for heavy ions. Keep several things in mind about what was done here: We assume that we can isolate hot nuclear matter effects by calculating RAA due to a (Glauber guided) superposition of d+Au collisions. Perhaps not! The role of Glauber uncertainties (mostly Ncoll) needs to be understood in detail. The systematic uncertainties should be considered tentative until then. We believe that fitting the RdAudata, rather than RCP, will provide greater precision when estimating the CNM baseline RAA for Au+Au and Cu+Cu. Although the parameterization at each rapidity is precise, it would be more satisfying if the model worked well over the full d+Au rapidity range! We need to repeat this exercise for the Cu+Cu data (easy enough to do, did not have time yet). Tony Frawley, FSU

  46. Summary The PHENIX d+Au data at 200 GeV seem to follow the trend observed at lower energy of a rapid rise in the effective σbreakupat forward rapidity. The effective σbreakup appears to be roughly constant below y ~ 1.25 at 200 GeV. The RAA(CNM) estimated from the fits to the RdAu data show significantly stronger suppression at |y|=1.7 than at y=0. The measured suppression beyond the estimated RAA(CNM) values, presumably due to hot nuclear matter effects, seems to be very similar at y=0 and |y|=1.7 at about 50%. Tony Frawley, FSU

  47. What next Calculate RAA(CNM) for Cu+Cu. Investigate the transverse momentum dependence. Understand the role of Ncoll uncertainties better. Do it all again with RdAu instead of RCP. Tony Frawley, FSU

  48. Backup Tony Frawley, FSU

  49. EPS08 parameterization Tony Frawley, FSU

  50. Existing RHIC Data - Au+Au Tony Frawley, FSU

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