April 21, 2006 X. R. Wang, DIS2006, Tsukuba, Japan 1

Charm Production at Large Rapidities in pp and

dAu Collisions at RHIC

Xiaorong Wang for PHENIX collaboration

New Mexico State University

Xiaorong Wang, SQM 2006 2April 21, 2006

The PHENIX Detectors

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

golddeuteron

Xiaorong Wang, SQM 2006 3April 21, 2006

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

PHENIX Preliminary

Au-goingd-going

Direction

High pT light hadrons

Xiaorong Wang, SQM 2006 4April 21, 2006

Gluon Shadowing in Heavy Nucleus

X

y

yield

Universal

)(ˆ)()( 2121 zDdxFxFd QQxxQQpp

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

Xiaorong Wang, SQM 2006 5April 21, 2006

Shadowing at Forward rapidity in dAu collisions

Color Glass Condense Dynamic Multiple

Scattering Power Correction

J. Qiu & I. Vitev

D. Kharzeev & K. Tuchinhep-ph/0310358

Power correction only

CGC

Xiaorong Wang, SQM 2006 6April 21, 2006

Recombination

“Explains” light hadron yields in forward and backward rapidities Input: low pT forward

/backward hadron distributions

Expect similar effects on open charm(?)

Measurement of charm yields could provide additional constrains on these models

H

Xiaorong Wang, SQM 2006 7April 21, 2006

Prompt µ background subtraction

Punch-through hadrons: Data driven method to Estimate

attenuation

Decay muons: Vertex distribution analysis

Open Charm Analysis Techniques

Decay muons

Punch-through hadronsPrompt muons ?

Gap2 Gap3 Gap4

Prompt+decay muons

Hadron

num

ber

of

trac

ks

00 37.0)( NeNiNiL

Muondetector

absorber

decay

punchthrough

prompt

Xiaorong Wang, SQM 2006 8April 21, 2006

Comparison Prompt - pt spectrum with theory

FONLL: Fixed Order next-to-leading order terms and Next-to-Leading-Log large pT resummation.

FONLL and PYTHIA calculation under predicted PHENIX Data at forward rapidity,

Run2pp -

FONLL: Solid line and bandWithout scaling the charm contribution: dotted linembsyspythiasysdata

statdy

dy

cc

).(.).(105.0

.)(013.0243.0|

049.0087.0

6.1

Xiaorong Wang, SQM 2006 9April 21, 2006

Prompt ’s pT spectra in dAu collisions and RdAu

North Arm: d going direction;

South Arm: Au going direction

Xiaorong Wang, SQM 2006 10April 21, 2006

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

Xiaorong Wang, SQM 2006 11April 21, 2006

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

Xiaorong Wang, SQM 2006 12April 21, 2006

pT broadening: Cronin Effect

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

Xiaorong Wang, SQM 2006 13April 21, 2006

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!

Xiaorong Wang, SQM 2006 14April 21, 2006

Backup

Xiaorong Wang, SQM 2006 15April 21, 2006

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

D±±, … , c++,

B± ±

± ±

* + -

q q * + -

J/,… + -

, , + -

charge asymmetric

charge symmetric

Xiaorong Wang, SQM 2006 16April 21, 2006

Nuclear Modification Factor: RdAu (decay from light hadrons)

PHENIX Preliminary PHENIX Preliminary

Au-goingd-going

Direction

RdAu vs pTRdAu vs η

Xiaorong Wang, SQM 2006 17April 21, 2006

Experimental Challenge

Prompt Muons

Punch-through hadrons

Decay Muon

Xiaorong Wang, SQM 2006 18April 21, 2006

PHENIX muon arms “x” coverage

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

gluons in Pb / gluons in p

X

PYTHIA open charm simulation

Particle production in the d direction (north) is sensitive to the small-x parton distribution in the Au nuclei; whereas in the gold (south) is sensitive to the large-x in Au

Xiaorong Wang, SQM 2006 19April 21, 2006

Xiaorong Wang, SQM 2006 20April 21, 2006