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Muon Production in Forward and Backward Rapidities in dAu Collisions at RHIC. Ming X. Liu Los Alamos National Lab (for the PHENIX Collaboration) Key words heavy quark semileptonic decay light hadron weak decay (anti)shadowing/CGC. θ. Motivation. - PowerPoint PPT Presentation
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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
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