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

Mike Leitch - Los Alamos National LaboratoryFor E866/NuSea & the PHENIX Collaboration

leitch@lanl.gov

PHENIX Muon Meeting, Santa Fe, June 16-18, 2003

Gluon shadowing & energy loss in nuclei J/ production mechanisms & absorption Cronin effect (pT broadening) PHENIX measurements and charm in d-Au Summary

FNAL E866/NuSea

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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

Rat

io(W

/Be)

1.0

0.9

0.8

0.7

Drell-Yan

E866 R(W/Be)E772 R(W/D)

X2

PRL 83, 2304 (1999) (hep-ex/9906010) Eskola, Kolhinen, Vogt hep-ph/0104124

PHENIX μPHENIX e

E866 (mid-rapidity)NA50

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• 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)

cc

800 GeV p-A (FNAL)PRL 84, 3256 (2000)

HadronizedJ/

cc

open charm: no A-depat mid-rapidityFNAL E866/NuSea

Donald Isenhower, Mike Sadler, Rusty Towell, Josh Willis Abilene Christian

Don Geesaman, Sheldon Kaufman, Bryon Mueller ANLChuck Brown, Bill Cooper FNALGus Petitt, Xiao-chun He, Bill Lee Georgia StateDan Kaplan IITTom Carey, Gerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss,

Jen-Chieh Peng, Paul Reimer, Walt Sondheim LANLMike Beddo, Ting Chang, Vassili Papavassiliou, Jason Webb New

Mexico St. Paul Stankus, Glenn Young ORNLCarl Gagliardi, Bob Tribble, Eric Hawker, Maxim Vasiliev Texas A & M Don Koetke Valparaiso

Nuclear Dependence of charm in E866 ANA

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Gluon Shadowing – Largely Unknown

Kopeliovich, Tarasov, & Hufnerhep-ph/0104256

Eskola, Kolhinen, Vogt hep-ph/0104124

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

PHENIX μPHENIX eE866 (Y~0)

Eskola

Kopeliovich

Shadowing (only) for d+Au -> J/

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J/ at fixed target: Absorption at mid-rapidity

• Significant nuclear dependence of cross section is observed• Power law parameterization = A

= 0.92 (E772, PRL 66 (1991) 133) (limited pT acceptance bias) = 0.919 ± 0.015 (NA38, PLB 444 (1998)516) = 0.954 ± 0.003 (E866 @ xF=0. PRL 84 (2000),3258 ) = 0.934 ± 0.014 (NA50, QM2001)

• Absorption model parameterization = 6.2 mb (NA38/50/51) to 4.4 mb (NA50, QM2002)

• Small difference in between J/ and (2S) (E866)(J/) – (S) ~ 0.02-0.03 @ xF = 0

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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 = 0.94Now 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) = 0.76then 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)) ~ 0.91i.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 ~ 0.86Kopeliovich: R(Au/d)(mu+mu-) ~ (0.66)(0.40) = 0.26 or alpha ~ 0.71

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Color-dipole modelKopeliovich, Tarasov, Hufner

Nucl.Phys. A696 (2001) 669-714(hep-ph/0104256)

1. absorption2. dynamic calc. of gluon

shadowing3. anti-shadowing from

Eskola4. energy loss5. Decay of J/(base

calculation is for )

cc

E866 J/ data

(4) Full calculation(+ dE/dx & Chi->J/

(1) quark-shad+ FS absorp.

(3) anti-shad

(2) gluonshadowing

Energy loss of gluons in nuclei

Energy loss of incident parton shifts effective xF and produces nuclear suppression which increases with xF

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800 GeV 800 GeV

Drell-Yan

J/ J/120GeV

Gavin & Milana Energy Loss (from R. Vogt, hep-ph/9907317)

ANA

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PT Broadening at 800 GeV

(pT) shape is independent of xF & same for NA3 at a lower energy(curves are with A slightly different for each)

)011.06.1()( 2TTT ppAp

E772 & E866: p-A at 800 GeV

Drell-Yan

J/ & ’

Upsilons

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Systematics of PT Broadening

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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

Proton Pion

χ,1,2 J/Ψ 30% 37%

Ψ΄ J/Ψ 5.5% 7.6%

Meson M(GeV) R(Fm)BE

(MeV)

J/Ψ 3.1 .45 ~640

Ψ΄ 3.7 .88 ~52

χC 3.5 .70

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E769 250 GeV ± PRL 70,722 (1993)

WA82 340 GeV -

PRB 284,453 (1992)

• Open charm has little or no nuclear dependence

= 1.00± 0.05 (E769 250GeV +A)

= 0.92 ±0.06 (WA82 340GeV +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, =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.

Open Charm Nuclear Dependence : xF Dependence?

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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.

Open Charm Measurements

0eD K

0D K

0 0e eD D e e K K

0 0eD D e K K

0 0D D K K

c c

0DK+

-

0D

e+

D*0

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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.

(Comparison of North and South J/ 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)

~ 232 J/’s = 164 MeV

South Muon Arm

~ 356 J/’s = 145 MeV

Dimuon Mass (GeV/c)

North Muon Arm

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NorthMuon Arm

SouthMuon Arm

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

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

Centrality Dependence with expected statistics & Vogt calculations

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

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

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Eskola

Kopeliovich

Shadowing for d+Au -> J/

Summary800 GeV p-A (FNAL)PRL 84, 3256 (2000)

HadronizedJ/

cc

J/ 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/ 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/ suppression for normal nuclear matter is critical if the J/ 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

open charm

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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, …

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Peter Jacobs

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Backup slidesBackup slides

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South PHENIX Muon Arm

200 GeV d+Au

opposite-sign pairssame-sign pair bkgd

Dimuon Mass (GeV/c)

~ 232 J/’s3.18 ± .03 GeV = 164 ± 27 MeV

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/’s expected from the L ~ 2.7 nb-1

d-Au run (w/o shadowing)• ~ 1000/arm for +-

• ~ 400 for e+e-

p-p run (just completed) may give ~ 300/arm J/’s

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North PHENIX Muon Arm

200 GeV d+Au

~ 356 J/’s3.11 ± .01 GeV = 145 ± 11 MeV

opposite-sign pairssame-sign pair bkgd

Dimuon Mass (GeV/c)

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

Comparison of North and South J/ 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

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NA50 - Phys. Lett B 521 (2002) 195

Binary scaling

4.4 mb absorption7.1 mb absorption

200A GeVAu-Au J/ ee

We can not discriminate between scenarios, given our present statistical accuracy

PHENIX

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Parton Energy Loss in Nuclei for Drell-Yan – Kopeliovich Model

Johnson, Kopeliovich et al., hep-ph/0105195

Shadowing

dE/dx &Shadowing

Drell-Yan data from E772 (PRL 64, 2479 (1990))

/2 JE

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)

22/1 xml Ncoherence

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Process Dependence of Shadowing?

• Ordinary shadowing is process independent and is a “property” of the structure function in a nucleus

Kopeliovich et al hep-ph/0104256& hep-ph/0205151

In the color-dipole model suppression at large xF (small x2) is much stronger for the J/ than for open-charm• but here much of the “shadowing” is “higher-twist final-state c-cbar interactions”

opencharm

J/

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)

PHENIX will look for this in d-Au measurements by comparisons of rapidity dependence of suppression between open- and closed-charm.