Charm in p(d)-A Collisions: E866/FNAL & PHENIX

1. FNAL E866/NuSea Charm in p(d)-A Collisions: E866/FNAL & PHENIX Mike Leitch - Los Alamos National Laboratory For E866/NuSea & the PHENIX Collaboration leitch@lanl.gov PHENIX Muon Meeting, Santa Fe, June 16-18, 2003 • Gluon shadowing & energy loss in nuclei • J/Y production mechanisms & absorption • Cronin effect (pT broadening) • PHENIX measurements and charm in d-Au • Summary

2. PRL 83, 2304 (1999) (hep-ex/9906010) Eskola, Kolhinen, Vogt hep-ph/0104124 Drell-Yan Ratio(W/Be) 1.0 0.9 0.8 E866 R(W/Be) E772 R(W/D) 0.7 X2 PHENIX μ PHENIX e E866 (mid-rapidity) NA50 Physics Issues in heavy-quark production in nuclei - Shadowing • Shadowing of gluons  depletion of the small x gluons • Very low momentum fraction partons have large size, overlap with neighbors, and fuse to thus enhancing higher population at higher momenta at the expense of lower momenta • Or, coherent scattering resulting in destructive interference for coherence lengths longer than the typical intra-nucleon distance

3. 800 GeV p-A (FNAL) PRL 84, 3256 (2000) FNAL E866/NuSea Hadronized J/Y? • J/Ψ and Ψ’ similar at large xF where they both correspond to a traversing the nucleus • but Ψ’ absorbed more strongly than J/Ψ near mid-rapidity (xF ~ 0) where the resonances are beginning to be hadronized in nucleus • open charm not suppressed (at xF ~ 0) Nuclear Dependence of charm in E866 open charm: no A-dep at mid-rapidity Donald Isenhower, Mike Sadler, Rusty Towell, Josh Willis Abilene Christian Don Geesaman, Sheldon Kaufman, Bryon Mueller ANL Chuck Brown, Bill Cooper FNAL Gus Petitt, Xiao-chun He, Bill LeeGeorgia State Dan Kaplan IIT Tom Carey, Gerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss, Jen-Chieh Peng, Paul Reimer, Walt Sondheim LANL Mike Beddo, Ting Chang, Vassili Papavassiliou, Jason WebbNew Mexico St. Paul Stankus, Glenn Young ORNL Carl Gagliardi, Bob Tribble, Eric Hawker, Maxim Vasiliev Texas A & M Don Koetke Valparaiso

4. Eskola, Kolhinen, Vogt hep-ph/0104124 Shadowing (only) for d+Au -> J/Y Eskola PHENIX μ PHENIX e E866 (Y~0) Kopeliovich, Tarasov, & Hufner hep-ph/0104256 Kopeliovich Gluon Shadowing – Largely Unknown PHENIX μ+μ- (Au) • Gluon shadowing for J/Ψ’s in PHENIX μ acceptance; large uncertainty: • Eskola… : ~ 0.8 vrs Kopeliovich… : ~ 0.4 • Must be measured

5. J/Y at fixed target: Absorption at mid-rapidity • Significant nuclear dependence of cross section is observed • Power law parameterization s = sN * Aa a = 0.92 (E772, PRL 66 (1991) 133) (limited pT acceptance bias) a = 0.919 ± 0.015 (NA38, PLB 444 (1998)516) a = 0.954 ± 0.003 (E866 @ xF=0. PRL 84 (2000),3258 ) a = 0.934 ± 0.014 (NA50, QM2001) • Absorption model parameterization • = 6.2 mb (NA38/50/51) to 4.4 mb (NA50, QM2002) • Small difference in a between J/Y and Y(2S) (E866) a(J/Y) – a(Y(2S)) ~ 0.02-0.03 @ xF = 0

6. What might be expected for alpha for mid-rapidity J/Psi's at RHIC? From our measurements at FNAL and those at NA38/50 we see (taking a rough average), alpha = 0.94 Now if we believe there is strong anti-shadowing in the x2=0.1 region, as shown by Eskola and used also by Kopeliovich; then the FNAL and CERN experiments are in this range and their alpha values are larger due to this anti-shadowing. So lets take out this anti-shadowing from alpha and see what's left over, R(Au/d) = (197/2)^(alpha-1) = (197/2)^(0.94-1) = 0.76 then Eskola anti-shadowing in the ratio is about 1.15, so R(Au/d)[w/o anti-shad] ~ 0.66 and alpha[w/o anti-shad] = 1 + (ln(R)/ln(A/d)) ~ 0.91 i.e. the effective alpha for J/Psi without anti-shadowing from the FNAL and CERN experiments is about 0.03 lower. Then at RHIC energies for central rapidity Eskola predicts little or no shadowing, so this alpha = 0.91 would be the expectation if this is true (no shadowing at central rapidity) On the other hand, Kopeliovich predicts a reduction in the gluon density at x2 ~ 1.5e-2 (about where e+e- J/Psi's are for us) to about 0.75. So for Kopeliovich shadowing we would get for central rapidity, R(Au/d)[Kopeliovich,y=0] ~ (0.66)(0.75) = 0.50 or alpha = 0.85 For the numbers above, the difference between no shadowing and "Kopeliovich“ shadowing is 0.91 -> 0.85 in alpha, or 0.66 -> 0.50 in the Au/d ratio at mid-rapidity. At forward rapidity (i.e. for J/Psi -> mu+mu-) the effect should be much stronger, with Eskola showing a reduction in the gluons to about 0.80 and Kopeliovich to about 0.40, i.e., Eskola: R(Au/d)(mu+mu-) ~ (0.66)(0.80) = 0.53 or alpha ~ 0.86 Kopeliovich: R(Au/d)(mu+mu-) ~ (0.66)(0.40) = 0.26 or alpha ~ 0.71

7. E866 J/Y data (3) anti-shad (1) quark-shad + FS absorp. (2) gluon shadowing (4) Full calculation (+ dE/dx & Chi->J/Y) • absorption • dynamic calc. of gluon shadowing • anti-shadowing from Eskola • energy loss • Decay of  J/Y (base calculation is for ) Energy loss of gluons in nuclei Energy loss of incident parton shifts effective xF and produces nuclear suppression which increases with xF Color-dipole model Kopeliovich, Tarasov, Hufner Nucl.Phys. A696 (2001) 669-714 (hep-ph/0104256)

8. 800 GeV 800 GeV J/Y J/Y 120 GeV Drell-Yan Gavin & Milana Energy Loss (from R. Vogt, hep-ph/9907317)

9. PT Broadening at 800 GeV E772 & E866: p-A at 800 GeV Upsilons Drell-Yan a(pT) shape is independent of xF & same for NA3 at a lower energy (curves are with A slightly different for each) J/Y & Y’

10. Systematics of PT Broadening

11. Feeding of J/Ψ’s from Decay of Higher Mass Resonances E705 @ 300 GeV/c, PRL 70, 383 (1993) • Large fraction of J/Ψ’s are not produced directly • Nuclear dependence of parent resonance, e.g. χC is probably different than that of the J/Ψ • e.g. in proton production ~30% of J/Ψ’s will have effectively stronger absorption because they were actually more strongly absorbed (larger size) χC’s while in the nucleus

12. E769 250 GeV ± PRL 70,722 (1993) Open Charm Nuclear Dependence : xF Dependence? • Open charm has little or no nuclear dependence a = 1.00± 0.05 (E769 250GeV p+A) a = 0.92 ±0.06 (WA82 340GeV p+A) a = 1.02 ±0.03 ±0.02 (E789 800GeV p+A) • This is consistent with that there being little nuclear shadowing in the x region probed by the fixed target charm experiments. • Significant nuclear suppression is reported in large xF region (WA78, a=0.81 ± 0.05). This could be due to nuclear shadowing in small x (large xF), but this is not well understood. • At RHIC, we can probe x values much smaller than for fixed target and may observe nuclear shadowing effect in charm production. WA82 340 GeV - PRB 284,453 (1992)

13. Open Charm Measurements e+ p0 Motivation • Mainly produced from gluon fusion  sensitive to initial gluon density and gluon distribution. • Energy loss when propagating through dense medium. • Baseline measurement for charmonium suppression. • A silicon vertex detector would allow direct measurement via the displaced vertex, but for now we rely on the semi-leptonic decay modes. D*0 K+ m- nm

14. South Muon Arm New results from the PHENIX muon and electron arms for d-Au collisions are beginning to come out from this years data and should shed light on the question of shadowing for gluons, as well as provide a baseline for high-luminosity Au-Au measurements in the next RHIC run. ~ 232 J/Y’s s = 164 MeV Dimuon Mass (GeV/c) North Muon Arm (Comparison of North and South J/Y yields not instructive at this stage since we are only beginning to study efficiency issues which could have large effects and the data samples are not identical) ~ 356 J/Y’s s = 145 MeV Dimuon Mass (GeV/c)

15. South Muon Arm North Muon Arm FAKE data points to illustrate statistical power of d-Au data just taken (there will be additional systematic uncertainties)

16. Centrality Dependence with expected statistics & Vogt calculations FAKE data points to illustrate statistical power of d-Au data just taken (there will be additional systematic uncertainties)

17. Centrality dependence of absorption in simple Eikonal picture from Lars Gerland (for p-A)

18. FAKE data points to illustrate statistical power of d-Au data just taken (there will be additional systematic uncertainties)

19. 800 GeV p-A (FNAL) PRL 84, 3256 (2000) Hadronized J/Y? Summary open charm • J/Y suppression has a rich variation with kinematic variables, i.e xF and pT • gluon shadowing, absorption, parton energy-loss and pT broadening all important • J/Y is complicated by feed-down from higher mass resonances • open-charm has no nuclear dependence at mid-rapidity (but this doesn’t shed any light on shadowing at small x) • Understanding J/Y suppression for normal nuclear matter is critical if the J/Y is to be used as a probe for hot high-density matter (QGP) in heavy-ion collisions • At RHIC the effect of shadowing is very uncertain with predictions that vary by large factors. So it is quite important to measure shadowing Shadowing for d+Au -> J/Y Eskola Kopeliovich

20. U.W. Theory Institute (INT), d-Au week, 2-6 June 2003 • 2 June – Francois Arleo, ECT, “Energy loss of hard partons in cold and hot QCD media”. • 3 June – David d-Enterria, Columbia Univ, “Hard scattering in Au+Au, D+Au and p+p collisions at sqrt(s_nn) = 200 GeV; Latest result from PHENIX at RHIC” • 4 June – Peter Jacobs, LBNL, “Hard scattering in Au+Au, D+Au and p+p collisions at sqrt(s_nn) = 200 GeV; Latest result from STAR at RHIC” • 5 June – Carlos Salgado, CERN, “Higt-pT particle production in nuclear collisions” • 5 June – Rainer Fries, Duke, “Hadronization in Heavy Ion Collisions: Recombination and Fragmentation” • 6 June – Mike Leitch, LANL, “Charm Production in E866/FNAL & PHENIX” • 6 June – Ramona Vogt, LBNL, “J/Psi production at SPS and RHIC” Participants: Arleo, Aurenche, Bass Burward-Hoy, d-Enterria, Fries, Gagliardi, Gerland, Jacak, Jacobs, Jalilian-Marian, Kunde, Leitch, Qiu, Randrup, Rischke, Salgado, Tuchin, Vitev, Vogt, Weidemann, Zhang, …

21. Peter Jacobs

24. Backup slides

25. 200 GeV d+Au opposite-sign pairs same-sign pair bkgd ~ 232 J/Y’s 3.18 ± .03 GeV s = 164 ± 27 MeV Dimuon Mass (GeV/c) South PHENIX Muon Arm • South Arm operating at optimal level after extensive repair work during the shutdown before the d+Au run • less than 1/3 of d+Au data in this analysis • trigger and other efficiencies still under study • Number of J/Y’s expected from the L ~ 2.7 nb-1 • d-Au run (w/o shadowing) • ~ 1000/arm for m+m- • ~ 400 for e+e- • p-p run (just completed) may give ~ 300/arm J/Y’s

26. North PHENIX Muon Arm 200 GeV d+Au • d+Au run is 1st for North Muon arm • mass resolution already close to optimal even without final alignment constants • this analysis from less than 1/3 of the d+Au data • efficiencies, especially for the trigger, still largely unknown for this quick analysis opposite-sign pairs same-sign pair bkgd ~ 356 J/Y’s 3.11 ± .01 GeV s = 145 ± 11 MeV Comparison of North and South J/Y yields not instructive at this stage since we are only beginning to study efficiency issues which could have large effects and the data samples are not identical Dimuon Mass (GeV/c)

27. We can not discriminate between scenarios, given our present statistical accuracy 200A GeVAu-Au J/Y ee PHENIX Binary scaling 4.4 mb absorption 7.1 mb absorption NA50 - Phys. Lett B 521 (2002) 195

28. Parton Energy Loss in Nuclei for Drell-Yan – Kopeliovich Model Johnson, Kopeliovich et al., hep-ph/0105195 Shadowing • Shadowing when coherence length, • is larger than nucleon separation • From E772 & E866 Drell-Yan data • With separation of shadowing • & dE/dz via Mass dependence • In the color-dipole model: • dE/dz ~ -2.7 ± .4 ± .5 GeV/fm • PRC 65, 025203 (2002) dE/dx & Shadowing Drell-Yan data from E772 (PRL 64, 2479 (1990))

29. open charm J/Y Process Dependence of Shadowing? • Ordinary shadowing is process independent and is a “property” of the structure function in a nucleus • Jorg Raufeisen (private comm.) • Gluon shadowing in the color-dipole model for Au • here only the higher-twist shadowing causes the difference between open and closed charm • (anti-shadowing from Eskola - ad hoc) • also see, PRD 67, 054008 (2003) • In the color-dipole model suppression at large xF (small x2) is much stronger for the J/Y than for open-charm • but here much of the “shadowing” is “higher-twist final-state c-cbar interactions” Kopeliovich et al hep-ph/0104256 & hep-ph/0205151 PHENIX will look for this in d-Au measurements by comparisons of rapidity dependence of suppression between open- and closed-charm.