Transverse and Longitudinal Dynamics at RHIC

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Transverse and Longitudinal
Dynamics at RHIC
Paweł

Staszel,
Marian Smoluchowski Institute of Physics
Jagiellonian University
IV Polish Workshop
on Relativistic Heavy-Ion Collisions
Kraków, 17–18.08.2007
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Outline
1. Detector setup.
2. General (bulk) characteristics of nucleus-nucleus
reactions.
3. Nuclear modification at mid-rapidity
4. Nuclear modification at forward rapidity
5. Elliptic Flow
6. Testing pQCD at large rapidities in p+p
7. Summary.
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Relativistic Heavy Ion Collider
Au+Au
d+Au
p+p
energies:
√sNN
=200GeV,
√sNN
=62GeV
Cu+Cu
PHOBOS
STAR
PHENIX
BRAHMS
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
B
Broad
Ra
Range
H
Hadron
M
Magnetic
S
Spectrometers
Tile Ring 1
Flow Ring 2
Si Ring 1
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Particle production and energy loss
Energy density:
Bjorken 1983
eBJ
= 3/2 ×(<Et
>/ πR2τ0
) dNch
/dη
assuming formation time t0
=1fm/c:
>5.0 GeV/fm
3
for AuAu @ 200 GeV
>4.4 GeV/fm
3
for AuAu @ 130 GeV
>3.7 GeV/fm
3
for AuAu @ 62.4 GeV



p p
y
y
BB
y
T
dyy
dy
dN
m cosh
)(
Total ΔE=25.7±2.1TeV
72GeV per participant
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Primary versus produced matter
• longitudinal net-kaon evolution similar as net-protonin |y|< 3 at RHIC (AuAu @ 200 GeV)
• strong “association”: net-kaon / net-lambda /net-proton?
BRAHMS
NA49
AGS
primary matter is concentrated
around y≈3 (δy≈2.0)
At 200GeV
created matter is at picked at y=0
7
P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
K-/K+ and antihyperon/hyperon
K-/K+ = exp((2μs -2μu,d
)/T)
pbar/p = exp(-6μu,d
/T)
μs
=0 ⇒

K-/K+ = (pbar/p)1/3
Fit shows that K
-/K
+ = (pbar/p)
1/4


μs
= ¼ μu,d
How μs
= ¼ μu,d
will work for hyperons?
Hbar/H = (pbar/p)
3/4
for Lambdas
= (pbar/p)
1/2
for Xis
= (pbar/p)
1/4
for Omegas
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Other characteristics versus pbar/p
pbar/p controls not only
anti-particle to particle ratios
but also K/π

ratios and K slopes
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
q
q
hadrons
leading
particle
leading particle
Schematic view of jet production

Particles with high pt’s (above ~2GeV/c)
are primarily produced in hard scattering
processes early in the collision
Experimentally →depletion of the high pt
region in hadron spectra

In A-A, partons traverse the medium
→Probe of the dense and hot stage

p+p experiments →hard scattered
partons fragment into jets of hadrons
If QGP→partons will lose a large
part of their energy
(induced gluon radiation)
→suppression of jet production
↔Jet Quenching
High pt
suppression &

jet quenching
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Charged hadron invariant spectra
AuAu @200GeV
Scaled N+N reference
RAA
=
Yield(AA)
NCOLL
(AA) ×

Yield(NN)
Nuclear Modification Factor
RAA
<1 ↔Suppression relative to
scaled NN reference
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Energy and system dependent
nuclear modification factors at h~0 and 1
• R AuAu
(200 GeV) < RAuAu
(63 GeV) < RCuCu
(63 GeV) for charged hadrons
• p+p at 63 GeV is ISR Data (NPB100), RHIC-Run6 will provide better reference
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Control measurement: d+Au @ √sNN
=200
[GeV/c]
T
p
12345
Nuclear Modification Factor
0.5
1
1.5
d+Au (MB)
Au+Au (0-10%)
=0η
Excludes alternative interpretation in terms of Initial State Effects


Supports the Jet Quenching for central Au+Au collisions
+ back-to-back azimuthal correlation and jet structure by STAR and PHENIX
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13
P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
RAuAu
(Y=0) ~ R
AuAu
(y~3)
for central Au+Au at √s = 200 GeV
• R AuAu
(Y=0) ~ RAuAu
(y~3) for pions and protons: accidental?
• Rapidity dependent interplay of Medium effect + Hydro + baryon transport
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Interpretation of suppression at forward y
• G. G. Barnafoldi et al.
Eur.
Phys. J. C49 (2007)333
• pQCD + GLV fit to RAA


L/λ
• assuming λ=1fm
• L~4/1.5fm at mid/forward
rapidity
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Differential flow at forward rapidity
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Examine d+Au at all rapidities
[GeV/c]
T
p
123456
d+Au
R
0
0.5
1
1.5
2
= 3.2η
-
h
[GeV/c]
T
p
123456
d+Au
R
0
0.5
1
1.5
2
= 2.2η
-
h
[GeV/c]
T
p
123456
d+Au
R
0
0.5
1
1.5
2
= 1η
2
-
+h
+
h
[GeV/c]
T
p
123456
d+Au
R
0
0.5
1
1.5
2
= 0η
2
-
+h
+
h
Cronin enhancement
Cronin enhancement
suppression
suppression
I. Arsene et al., BRAHMS PRL 93 (2004) 242303.
[GeV/c]
T
p
12345
CP
R
0
0.5
1
1.5
2
= 3.2η
-
h
[GeV/c]
T
p
12345
CP
R
0
0.5
1
1.5
2
= 2.2η
-
h
[GeV/c]
T
p
12345
CP
R
0
0.5
1
1.5
2
= 1η
2
-
+h
+
h
[GeV/c]
T
p
12345
CP
R
0
0.5
1
1.5
2
0-20%/60-80%
30-50%/60-80%
= 0η
2
-
+h
+
h
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
p+p at 200GeV – examine pQCD at large
y
preliminary- accepted for pub. in PRL
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Large y: pQCD versus data
μ=μF=μR=pT. CTEQ6 parton distribution functions.
KKP modified to obtain FFs for specific charges: D
π+ u
= (1+z)D
π0 u
; Dπ- u
= (1-z)Dπ0u
AKK reproduce STAR p+pbar at y~0, at large y gluons contribute in > 80%
KKP under predict p+pbar by factor of 10.
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Does baryon number transport extend to high pT
?
yb

=5.4
yb

=-5.4
y
pT
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
High energy density >>
nuclear density
-

〈δy〉≈2
-

25 TeV

left for
particle production
(local) Chemical equilibration
Onset of gluon saturation?
Summary
Strong transverse/elliptic
flow in y<3
Limiting
fragmentation
Non-hadronic

energy loss
through the medium in |y|<3:
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
I.Arsene
7, I.G. Bearden6, D. Beavis
1, S. Bekele
6
, C. Besliu
9, B. Budick5,
H. Bøggild
6 , C. Chasman1, C. H. Christensen
6, P. Christiansen
6, R. Clarke9, R.Debbe
1,
J. J. Gaardhøje6, K. Hagel
7, H. Ito10, A. Jipa
9, J. I. Jordre
9, F. Jundt
2, E.B. Johnson10,
C.E.Jørgensen
6, R. Karabowicz3, N. Katryńska3, E. J. Kim4, T.M.Larsen11, J. H. Lee1,
Y. K. Lee4, S.Lindal
11, G. Løvhøjden2, Z. Majka3, M. Murray10, J. Natowitz7, B.S.Nielsen
6,
D. Ouerdane
6, R.Planeta
3, F. Rami
2, C. Ristea6, O. Ristea
9, D. Röhrich8,
B. H. Samset
11, D. Sandberg
6, S. J. Sanders
10, R.A.Sheetz
1, P. Staszel
3,
T.S. Tveter
11, F.Videbæk1, R. Wada
7, H. Yang6, Z. Yin8,and I. S. Zgura
9
1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France
3Jagiellonian University, Cracow, Poland,
4Johns Hopkins University, Baltimore, USA,
5New York University, USA
6Niels Bohr Institute, University of Copenhagen, Denmark
7Texas A&M University, College Station. USA,
8University of Bergen, Norway
9University of Bucharest, Romania,
10University of Kansas, Lawrence,USA
11
University of Oslo Norway
48 physicists from 11 institutions
The BRAHMS Collaboration
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
BACKUP SLIDES
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
RdAu
and RAA
for anti-protons and pions @200
BRAHMS PRELIMINARY

suppression for π-
but stronger for AuAu
•both RdA
and RAA
show enhancement for p-bar
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Nuclear modification factors (RCP
, RAuAu
)
for p,K,p at y~3.1
• Suppression for pions and kaons: RAuAu
: π

< K < p
• RAuAu


Rcp (<Ncoll>,<Npart> for 40-60% ~ 70,56)
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Flow at forward rapidity
• missing low-pt fraction is important for
integrated v2 from FS (can explain about
20% change)
dN 1
dηdpt

(1 + 2v1
cosϕ

+ 2v2
(η,pt
)cos2ϕ)
dN
dηdpt

=
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Constituent quark scaling
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
... more on RAA
rapidity dependence
•Similar level of suppresion for
central collisions
•At forward rapidity R
AA
shows
stronger rise towards peripheral coll.
(surface -> volume emmission)
Looking for scaling: dN/dη

?
preliminary
BE: ε

= 3/2 ×(<E
t
>/ Sτ0
) dNch
/dη
S is transwers area of overlaping region
<Et
> dirived from π

and K spectra
Is the energy density the only parameter
that controls RAA
?
New pp data @62GeV will allow for
various comparisions at the same
rapidities
preliminary
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
•At 200 GeV: π-/π+
= 1.0, K
-/K+
= 0.95,
pbar/p = 0.75
•At 62 GeV
: π-/π+
= 1.0, K
-/K+
= 0.84,
pbar/p = 0.45,
•At |y|<1 matter⇔antimatter
Anti-particle to particle ratios
• pbar/p verus K-/K+
: good statistical model
description with μB
= μB
(y) with T~170MeV
•But this describes also energy depencency at
y=0 ⇒only μB controls the state of matter
•STAR and NA47 measures pbar/p versus
Ξ-/Ξ+
Chemical freeze-out

BRAHMS PRELIMINARY
It is not true for p+p
BRAHMS PRELIMINARY
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
RAuAu

200 GeV
BRAHMS, PRL 91, 072305 (2003)
Cronin enhancement
Cronin enhancement
suppression at high pT
significant medium effects
suppression at high pT
significant medium effects
0.5
1.0
= 0η
0.5
1.0
12345
= 1η
12345
= 2.2η
12345
= 3.2η
12345
-
h
+
h
(0-10%)
AuAu
R (40-60%)
AuAu
R
cp
R
, GeV/c
T
p, GeV/c
T
p, GeV/c
T
p, GeV/c
T
p
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Strong rapidity
dependence
CuCu data consistent with
AuAu for the same Npart
pp
pp
pbar/π-
scaling with Npart
√sNN
=200GeV
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
K/π

ratios at η=3.1, Au+Au @200GeV
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Strong energy absorption model from a static 2D matter
source. (Insprired by

A.Dainese (Eur.Phys.J C33,495) and A.Dainese ,
C.Loizides and G.Paic (hep-ph/0406201) )


Parton spectrum using pp reference spectrum


Parton energy loss ΔE ~ q.L**2


q adjusted to give observed RAA

at η~1.
The change in dN/dη

will result in slowly rising RAA

.
The modification of reference pp spectrum causes the RAA

to be
approximately constant as function of η

.
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Summary
Large hadron multiplicities
Almost a factor of 2 higher than at SPS energy(↔higher ε)
Much higher than pp scaled results(↔medium effects)
p/π
show strong ηdependency
for given energy depend only on N
par
High-pT
suppression increases with energy for given centrality bin
weak dependency on rapidity of R
AA
which is consistent with surface
jet emission
RCP
can hide or enhance nuclear effects
At y=3.2 RAA
shows larger suppression than RdA

Identified hadron spectra
Good description by statistical model
Large transverse flow consistent with high initial density
v2(pt) is seem to not depend on rapidity
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
FS PID using RICH
Multiple settings
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
RdAu

Update: Identified Particle RdAu

at y~3


RdAu of identified particle consistent with published h-

results


dAu(π-)/dAu(π+): Valance quark isospin dominates in pp?
BRAHMS Preliminary
+ blue
-red
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P. Staszel -Jagiellonian University, Kraków
IV Polish Workshop on RHIC, Kraków 2007
BRAHMS
Limiting Fragmentation
Shift the dNch
/dη

distribution by the beam rapidity, and scale by 〈Npart
〉.
Lines up with lower energy ⇒

limiting fragmentation
Au+Au √sNN
=200GeV (0-5% and 30-40%)
Au+Au √sNN
=130GeV (0-5%)
Pb+Pb √sNN
=17GeV (9.4%)