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)

M. Liu DNP05

The PHENIX Detectors

South Muon arm : -1.2 > > -2.0 North Muon arm : 2.4 > > 1.2

golddeuteron

M. Liu DNP05

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

M. Liu DNP05

Gluon Shadowing in Heavy Nucleus

X

y

yield

Universal

)(ˆ)()( 2121 zDdxFxFd QQxxQQpp

From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.

M. Liu DNP05

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

M. Liu DNP05

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

M. Liu DNP05

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

M. Liu DNP05

RdAu from Open Charm

X

),(),(

2

2

QxGQxGR

p

AudAu or:

•Initial parton energy loss•recombination

M. Liu DNP05

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

M. Liu DNP05

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

M. Liu DNP05

pT broadening: Cronin Effect

Broadening of J/ pT distribution suggests initial scattering (maybe also energy loss) is important

M. Liu DNP05

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!

M. Liu DNP05

backup

RdA

0

0.2

0.4

0.6

0.8

1.0

1.2

M. Liu DNP05

Prompt Muon Yields

• Forward and backward

Probed X ranges in Au

forward

bwd

M. Liu DNP05

Sources of prompt muons (pT> 0.9GeV) (determined from Pythia)

D±±, … , c++,

B± ±

± ±

* + -

q q * + -

J/,… + -

, , + -

charge asymmetric

charge symmetric

M. Liu DNP05

Prompt muon and D correlation• Hard fragmentation

– large <Z>– Strong correlations

η (muon)

η(D)

pT (muons)

pT