Open Charm and Charmonium Production at Large Rapidity in d+Au Collisions at RHIC
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M. Liu DNP05
Open Charm and Charmonium Production at Large Rapidity in
d+Au Collisions at RHIC
Ming X. LiuLos Alamos National Lab
(for the PHENIX Collaboration)
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The PHENIX Detectors
South Muon arm : -1.2 > > -2.0 North Muon arm : 2.4 > > 1.2
golddeuteron
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Physics Questions
• Cold nuclear medium effects:– Parton distributions
• gluon (anti)shadowing• CGC
– Interactions with medium• Parton energy loss• QCD Power Correction
– Recombination
• New probes: – Charm
♦♦ ♦
Brahms (h++h-)/2
( =0, 1.0, 2.2) pT =1.75
♦♦
High pT light hadrons
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Gluon Shadowing in Heavy Nucleus
X
y
yield
Universal
)(ˆ)()( 2121 zDdxFxFd QQxxQQpp
From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.
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Shadowing: Color Glass or Dynamic Multiple Scattering Power Correction?
• A challenge!– Explore (x, Q) space
• pT (Q^2) evolution– Collision energy scan– Different probes: light vs heavy!
J. Qiu & I. Vitev
D. Kharzeev & K. Tuchinhep-ph/0310358
Power correction only
CCG
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Recombination • “Explains” light hadron yields
in forward and backward rapidities– Input: low pT forward
/backward hadron distributions• Expect similar effects on
open charm(?)• Charm + light quarks• Hard fragmentation-> minimal
effects?• No detailed calculation yet(?)
• Measurement of charm yields could provide additional constrains on these models
H
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The normalized muon event vertex distribution
Muons from light and heavy meson decays
Muondetector
absorber
Decay muons
Punch-through hadrons
Prompt muons ?
Open heavy flavor production can be measured through prompt muons
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RdAu from Open Charm
X
),(),(
2
2
QxGQxGR
p
AudAu or:
•Initial parton energy loss•recombination
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How about J/Psi?• _NO_ Recombination!• Gluon shadowing/saturation• Initial state parton energy loss• J/Psi final state nuclear
absorption has minimal effects on the shape
X
RdA
0
0.2
0.4
0.6
0.8
1.0
1.2
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Shadowing or Energy Loss ?
)1972( ppdA
• Shadowing is not enough
• Initial state energy loss?– Incoming gluons loss
energy before the hard collisions
– Affects low pT particle production in the FWD and BWD papidities
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pT broadening: Cronin Effect
Broadening of J/ pT distribution suggests initial scattering (maybe also energy loss) is important
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Summary and Outlook• Physics at Forward and Backward Rapidity:
– open charm– J/psi
• Observed: heavy ~ ligh hadrons– suppression in the forward – enhancement in the backward
• Causes for such effects are not very clear– Shadowing: CGC, Power correction– Initial state energy loss– recombination– Need more theoretical work
• Need/Like to have:– Lower energy dAu collisions: stay away from shadowing regions– Explore { x, Q, sqrt(s) } space -> (y, pT, sqrt(s)) experimentally
• Parton energy loss vs shadowing• pT evolution – shadowing vs power correction• Shadowing vs recombination
• Explore QCD dynamics in details in coming years!
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backup
RdA
0
0.2
0.4
0.6
0.8
1.0
1.2
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Prompt Muon Yields
• Forward and backward
Probed X ranges in Au
forward
bwd
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Sources of prompt muons (pT> 0.9GeV) (determined from Pythia)
D±±, … , c++,
B± ±
± ±
* + -
q q * + -
J/,… + -
, , + -
charge asymmetric
charge symmetric
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Prompt muon and D correlation• Hard fragmentation
– large <Z>– Strong correlations
η (muon)
η(D)
pT (muons)
pT
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