Muon Production in Forward and Backward Rapidities in dAu

Collisions at RHICMing X. Liu

Los Alamos National Lab(for the PHENIX Collaboration)

Key words– heavy quark semileptonic decay– light hadron weak decay– (anti)shadowing/CGC

M.X. Liu QM04

Motivation

• Nuclear medium effects in forward and backward directions in dAu reactions– Different “x” range: initial state

• (anti)shadowing/CGC

– Final state (co-moving): very much energy dependent

• Flavor dependence?– Heavy flavors

• Open charm, beauty

– Light hadrons

Au rest frame

C.M.F.

)(cos

Ep

pp

z

TT

~1000 GeV

~10 GeV

θ

yes

Mx

M.X. Liu QM04

Theoretical Predictions

Increasing y

I. Vitev nucl-th/0302002

D. Kharzeev hep-ph/0307037

y=0

y=+3

y=-3

Gluon Shadowing/Saturation

M.X. Liu QM04

Questions

1. What happens in the forward (d) AND backward (Au) directions?

2. Any collision centrality dependence?3. Charge dependence?

• h+ vs h-

4. Flavor dependence? • Light vs heavy quarks

M.X. Liu QM04

PHENIX Muon Detectors• Muon arms

– 1.2<|η|<2.4– Δφ=2π– P>2GeV/c– Triggers

• “Muons”– Stopped hadrons– Light meson

decays– Heavy decays

Au

d

M.X. Liu QM04

Measurement of Stopped Hadrons

Stopping power: Use shallow MuID absorber layers to select stopped

hadrons

for Ptot > 1.9GeV: muon contamination < 3%

Hadronic tail

Muon peak

M.X. Liu QM04

Muon Production

• Origins of muons– PYTHIA p+p @

√s=200GeV– low PT:

• light hadron decays

– high PT: • Heavy quark decays

Muon PT distribution%63)(

%99.99)(

%10)(

%10)(

vKBR

vBR

XbBR

XcBR

M.X. Liu QM04

Muons from Light Meson Decays

• Muon event collision vertex distribution

Muon

detector

absorber

Collisions Vertex Z

M.X. Liu QM04

Measurements of Light/Heavy • Muons from light

meson decays

• Prompt muon PT distributions

1. Light hadron punch-throughs(work in progress)

2. Charm/Beauty!

PT

vK

v

1.5 < PT < 2.0

M.X. Liu QM04

Centrality Dependence of Particle Production @Fwd/Bwd Directions

1. Stopped hadrons– Mesons + Baryons

2. Light mesons– Pions + Kaons

3. Heavy flavors– Charm + Beauty

%6040%,4020%,200

;),( %8860

XXcent

NN

NN

yPR

coll

coll

XXcent

TdAuCP

Au

d

M.X. Liu QM04

d

Au

Phenix Preliminary

Stopped Hadrons!

M.X. Liu QM04

dAu

Stopped Hadrons!

Phenix Preliminary

M.X. Liu QM04

dAu

Shadowing?Cronin effect &anti-shadowing?

Stopped Hadrons!

Phenix Preliminary

M.X. Liu QM04

RCP(y): Muons from Light Meson DecaysPhenix Preliminary

vK

v

RCP

M.X. Liu QM04

RCP(y): Charge DependencePhenix Preliminary

μ+

μ-

vK

v

M.X. Liu QM04

Answers to Previous Questions

1. What happens in the forward (d) AND

backward (Au) direction? ☺

2. Centrality dependence? ☺

3. Charge dependence? ☺• h+ vs h-

4. Flavor dependence? • Light vs heavy quarks

M.X. Liu QM04

Amazing Grace“I once was lost but now I am found”

BRAHMS preliminary

Au+Au at 200GeV (2003 BNL dAu PR)

BRAHMS preliminaryη=2η=0

M.X. Liu QM04

Summary and Outlook• RCP @ forward and backward rapidity

– Very different from y = 0 !• Forward : suppression!• Backward: enhancement!

– Parton scattering/energy loss– Parton (anti)shadowing

• Work in progress– Open heavy flavors– RCP with heavy flavors

Posters– <Q13>Anuj Purwar/Chun Zhang, “Charged hadron RCP

measurement using the Phenix Muon Arms for d-Au collisions at 200 GeV ”– <Q27>Dave Lee, “Muon production in forward and backward rapidity

in dAu collisions”– <Q3> Ken Read; <Q5> Youngil Kwon; <Q6> Andy Glenn.

2.2||2.1 dAu

M.X. Liu QM04

Backup Slides

M.X. Liu QM04

Probed “x” region of Au

Saturation?

shadowing

enhancement

EMC effect

Fermi Effect

Blue band: d directionShadowing/suppression regime

Yellow band: Au directionAnti-shadowing/Cronin regime

yes

Mx

M.X. Liu QM04

RCP(PT): muons from light meson decays

Phenix Preliminary

vK

v

M.X. Liu QM04

RCP from J/Psi

• Forward vs Backward

R.G. de CassagnacFriday/Parallel 3

M.X. Liu QM04

More on nuclear medium effects RdAu(PT , y,…)

• Energy dependent nuclear cross section

• Gluon shadowing model

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

backward

forward

M.X. Liu QM04

Check the selected hadron sample using event vertex

Tracks stop at gap2 or gap3 and 3 sigma muon exclusive

M.X. Liu QM04

Muon Event Vertex Distribution

1. MinBias event vertex

2. Muon event vertex

3. Normalized vertex

Z-vtx

1

3 = “2” / ”1”

2

Au

d

M.X. Liu QM04

Central Arms y =0