Transverse and LongitudinalDynamics at RHIC
Paweł Staszel, Marian Smoluchowski Institute of Physics
Jagiellonian University
SQM 2007 Levoča, 24–29.06.2007
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2P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Outline
Detector setup (by Michael).
• General (bulk) characteristics of nucleus-nucleus reactions.
• Nuclear modification at mid-rapidity
• Nuclear modification at forward rapidity
• Elliptic Flow
• Testing pQCD at large rapidities in p+p
• Summary.
3P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Particle production and energy loss
Energy density: Bjorken 1983
eBJ = 3/2 (<Et>/ R20) dNch/d
assuming formation time t0=1fm/c:
>5.0 GeV/fm3 for AuAu @ 200 GeV
>4.4 GeV/fm3 for AuAu @ 130 GeV
>3.7 GeV/fm3 for AuAu @ 62.4 GeV
p
p
y
y
BB
yT dyydy
dNm cosh)(
Total E=25.72.1TeV72GeV per participant
4P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Primary versus produced matter
• longitudinal net-kaon evolution similar as net-proton in |y|< 3 at RHIC (AuAu @ 200 GeV)• strong “association”: net-kaon / net-lambda /net-
proton?
BRAHMS
NA49
AGS
primary matter is concentrated around y3 (y2.0)
At 200GeVcreated matter is at picked at y=0
5P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
K-/K+ and antihyperon/hyperon
K-/K+ = exp((2s - 2u,d)/T)pbar/p = exp(-6u,d/T)s=0 K-/K+ = (pbar/p)1/3
Fit shows that K-/K+ = (pbar/p)1/4
s= ¼ u,d
How s= ¼ u,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
6P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Statistical model and s vserus u,d
Fits with statistical model provide similar u,d/s ratio with weak dependency on y.
This result is consistent with local net-strangeness conservation red line - s = 0black line – fit to BRAHMS data
B. Bieron and W. Broniowski Phys. Rev. C75 (2007) 054905
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7P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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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8P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
q
q
hadronsleadingparticle
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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9P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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
10P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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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11P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Control measurement: d+Au @ sNN=200
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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12P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
RAuAu(Y=0) ~ RAuAu(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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13P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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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14P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
K/ ratios at =3.1, Au+Au @200GeV
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15P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Differential flow at forward rapidity
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16P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Examine d+Au at all rapidities
Cronin enhancement Cronin enhancement suppression suppression
I. Arsene et al., BRAHMS PRL 93 (2004) 242303.
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17P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
RdAu centrality dependence for +
20-40%40-80% 0-20%
BRBRAHMS PRELIMINARY
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18P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
p+p at 200GeV – examine pQCD at large yPRL 98 (2007) 252001
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19P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Large y: pQCD versus data
μ=μF=μR=pT. CTEQ6 parton distribution functions. KKP modified to obtain FFs for specific charges: Dπ+
u = (1+z)Dπ0u ; D
π-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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20P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Does baryon number transport extend to high pT?
yb=5.4y
b=-5.4
y
pT
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21P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
p+p @ 62GeV results
22P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
High energy density >> nuclear density
- y 2 - 25 TeV left for particle production
(local) Chemical equilibration
Onset of gluon saturation?
SummaryStrong transverse/elliptic flow in y<3
Limitingfragmentation
Non-hadronic energy loss through the medium in |y|<3:
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23P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
I.Arsene7, I.G. Bearden6, D. Beavis1, S. Bekele6 , C. Besliu9, B. Budick5, H. Bøggild6 , C. Chasman1, C. H. Christensen6, P. Christiansen6, R. Clarke9,
R.Debbe1, J. J. Gaardhøje6, K. Hagel7, H. Ito10, A. Jipa9, J. I. Jordre9, F. Jundt2, E.B.
Johnson10, C.E.Jørgensen6, R. Karabowicz3, N. Katryńska3, E. J. Kim4, T.M.Larsen11, J. H.
Lee1, Y. K. Lee4, S.Lindal11, G. Løvhøjden2, Z. Majka3, M. Murray10, J. Natowitz7,
B.S.Nielsen6, D. Ouerdane6, R.Planeta3, F. Rami2, C. Ristea6, O. Ristea9, D. Röhrich8, B. H. Samset11, D. Sandberg6, S. J. Sanders10, R.A.Sheetz1, P. Staszel3, T.S. Tveter11, F.Videbæk1, R. Wada7, H. Yang6, Z. Yin8, and I. S. Zgura9
1Brookhaven National Laboratory, USA, 2IReS and Université Louis Pasteur, Strasbourg, France3Jagiellonian University, Cracow, Poland,
4Johns Hopkins University, Baltimore, USA, 5New York University, USA6Niels 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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24P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
BACKUP SLIDES
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25P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
RdAu and RAA for anti-protons and pions @200
BRAHMS PRELIMINARY
• suppression for - but stronger for AuAu• both RdA and RAA show enhancement for p-bar
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26P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Nuclear modification factors (RCP, RAuAu) for p,K,p at y~3.1
• Suppression for pions and kaons: RAuAu: < K < p
• RAuAu ≠ Rcp (<Ncoll>,<Npart> for 40-60% ~ 70,56)
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27P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Flow at forward rapidity
• missing low-pt fraction is important for integrated v2 from FS (can explain about 20% change)
dN 1ddpt 2(1 + 2v1cos +
2v2(,pt)cos2)
dN ddptd
=
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28P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Constituent quark scaling
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29P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
... more on RAA rapidity dependence
•Similar level of suppresion for central collisions•At forward rapidity RAA shows stronger rise towards peripheral coll. (surface -> volume emmission)Looking for scaling: dN/d ?
preliminary
BE: = 3/2 (<Et>/ S0) dNch/d S is transwers area of overlaping region <Et> dirived from 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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30P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
•At 200 GeV: -/+ = 1.0, K-/K+ = 0.95, pbar/p = 0.75 •At 62 GeV: -/+ = 1.0, K-/K+ = 0.84, pbar/p = 0.45,• At |y|<1 matterantimatter
Anti-particle to particle ratios
• pbar/p verus K-/K+ : good statistical model description with B= B(y) with T~170MeV•But this describes also energy depencency at y=0 only B controls the state of matter•STAR and NA47 measures pbar/p versus -/+
Chemical freeze-out
BRAHMS PRELIMINARY
It is not true for p+p
BRAHMS PRELIMINARY
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31P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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
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32P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Strong rapiditydependence
CuCu data consistent with AuAu for the same Npart
pp
pp
pbar/- scaling with Npart
sNN=200GeV
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33P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 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 E ~ q.L**2• q adjusted to give observed RAA at ~1.
The change in dN/d will result in slowly rising RAA .
The modification of reference pp spectrum causes the RAA to be approximately constant as function of .
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34P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Summary Large hadron multiplicities Almost a factor of 2 higher than at SPS energy( higher ) Much higher than pp scaled results( medium effects)
p/ show strong dependency for given energy depend only on Npar
High-pT
suppression increases with energy for given centrality bin weak dependency on rapidity of RAA 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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35P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
FS PID using RICH
Multiple settings
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36P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
RdAu Update: Identified Particle RdAu at y~3
• RdAu of identified particle consistent with published h- results• dAu(-)/dAu(+): Valance quark isospin dominates in pp?
BR
AH
MS
P
relim
inary
+ blue- red
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37P. Staszel - Jagiellonian University, KrakówSQM 2007, Levoča 2007
BRAHMS
Limiting FragmentationShift the dNch/d 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%)