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Particle Production, Correlations, and Jet Quenching at RHIC *. John Harris Yale University. * Relativistic Heavy Ion Collider. quark-hadron phase transition 2 x 10 12 Kelvin. Early Universe. National Geographic (1994) & Michael Turner. - PowerPoint PPT Presentation
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John Harris (Yale University) QCD@Work 2003, Bari, Italy
John HarrisYale University
Particle Production, Correlations, and
Jet Quenching at RHIC*
* Relativistic Heavy Ion Collider
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Early Universe
National Geographic(1994)
&Michael Turner
quark-hadronphase transition2 x 1012 Kelvin
John Harris (Yale University) QCD@Work 2003, Bari, Italy
“In high-energy physics we have concentrated on experiments in which we distribute a higher and higher amount of energy into a region with smaller and smaller dimensions.
In order to study the question of ‘vacuum’, we must turn to a different direction; we should investigate some ‘bulk’ phenomena by distributing high energy over a relatively large volume.”
T.D. Lee (Nobel Laureate)Rev. Mod. Phys. 47 (1975) 267.
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Lattice QCD Calculations
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John Harris (Yale University) QCD@Work 2003, Bari, Italy
Purpose of Relativistic Heavy Ion Physics
• Investigate High Density QCD Matter in Laboratory– Determine its properties
• Phase Transitions?– Deconfinement to Quark-Gluon Plasma– Chiral symmetry restoration
• Relevance?– Quark-hadron phase transition in early Universe– Cores of dense stars– High density QCD
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Outline
• Introduction• Relativistic Heavy Ion Collider• Particle Production and Correlations• Hard Scattering and Jet Quenching• Conclusions & Future Expectations
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Relativistic Heavy Ion Collider
RHIC
STARPHENIX
PHOBOSBRAHMS
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Au on Au Event at CM Energy ~ 130 A-GeV
Central Event
color code energy loss
beamview
side view
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Space-time Evolution of Collisions
e
space
time jet
Hard Scattering + Thermalization
AuAu
Exp
ansi
on
Hadronization
p K
Freeze-out
QGP
e
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Motivation for Particle Production and Correlations at RHIC
• Thermalization?
– Particle yields & ratios, strangeness
chemical equilibration (T, B)
– Spectra
thermal freezeout (Tfo) + collective flow ()
• Pressure gradients particle & energy flow?
– Particle Correlations
transverse (T) & elliptic flow (v2) pressure
• Timescales?
– Bose-Einstein (HBT) Correlations
space-time evolution, system shape and size
• Deconfinement?
– Effects of medium on J/, resonances, parton propagation
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Large Number of Produced Particles
dnch/d |=0 = 670
Ntotal ~ 7500
Note - at least 7500 x 2 > 15,000 q + q in final state
(also large number of gluons early)
originally 3 quarks x 2 nuclei x 197 nucleons ~1200 valence quarks
> 92% of (> 15,000) quarks in final state are produced
dN
ch/d
M. Baker (PHOBOS) QM2002
= - ln [ tan(/2)]
Au + Auat RHIC
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Boost-Invariance at Mid-rapidityd
Nch
/d M. Baker (PHOBOS) QM2002
Longitudinal Flow (Bjorken expansion)Boost invariant - central rapidity plateau
1ηcosh/m)(p
/m)coshη(pη),(p
η
y :Jacobian
22
STAR
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Energy Densities at RHIC
1
11
02
02 dy
dNm
Rdy
dE
R
TT
Bj Longitudinal expansion –
J.D. Bjorken, PRD27 (1983) 140.
R2
dydz 0
for Au+Au: R = 6.5 fm, R2 ~ 130 fm2
dET/d ~ 600 GeV <mT> dN/dy = 0.534 GeV (1150)
dET/d GeV/fm3 –dn/d GeV/fm3
PHENIX
30 x nuclear density > 4 x c
R2
dydz 0
John Harris (Yale University) QCD@Work 2003, Bari, Italy
General Particle Ratios Chemical Equilibrium
Statistical Model fits particle ratios for 200 GeV Au + Au:
T = 177 MeV B = 29 MeV
John Harris QCD@Work 2003, Bari, Italy
Elliptic Flow – a Probe of Early Dynamics
XZ-plane - the reaction plane
Transverse Plane
22
22
xy
xy
XY
Azimuthal anisotropy elliptic flow measures response of the system to early pressure the system’s ability to convert original spatial anisotropy into momentum anisotropy
• sensitive to early dynamics of initial system
2cos2 vx
y
p
patan
v2: 2nd Fourier harmonic coefficient of azimuthal distribution of particles with respect to the reaction plane measures elliptic flow 2cos2 v
John Harris QCD@Work 2003, Bari, Italy
Hydrodynamic Calculation of Elliptic Flow
P. Kolb, J. Sollfrank, and U. Heinz
Contours of equal energy density
Au+Au at b=7 fm
= 3.2 fm/c = 8 fm/c
y (f
m)
x (fm)
John Harris QCD@Work 2003, Bari, Italy
Charged Particle Elliptic Flow (v2)
STAR PRL87 (2001)182301
STAR
Evidence that initial spatial asymmetry is efficiently translated into momentum space anisotropy (as in hydrodynamics)Increasing pressure gradients in the system
RG + QGPResonancegas
Mass dependence of V2(pT) sensitive probe of QCD EOS P (T)Rapid pressure buildup, explosive hydrodynamic expansionHydrodynamics needs quark-gluon softening of the hadronic EOS P. Huovinen, P. Kolb, U. Heinz & indepedently D. Teaney et al. also CM Ko et al., M. Bleicher et al., J. Kapusta et al.
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Characteristics of RHIC Collisions from Experiment
Summary of Soft Physics
from the > 40 refereed journal publications from RHIC experiments:
global observations:
Large produced particle multiplicities dnch/d |=0 = 670, Ntotal ~ 7500
92% of (>15,000) quarks of final state are produced quarks
Large energy densities dn/ddET/d GeV/fm3 –Large elliptic flow Large early pressure gradients and gluon densities
“chemical” equilibration:
Small net baryon density K+/K-,B/B ratios) B ~ 25 - 40 MeV
Quark coalescence B/B ratios)
Chemical Freezeout T from global particle ratios) T = 177 MeV, B = 29 MeV
“thermal” equilibration :
Thermal freezeout + large transverse flowTFO = 100-110 MeV, T = 0.5 – 0.6c
expansion dynamics:
No long-lived mixed phase (from Bose-Einstein correlations)
Short chemical-to-thermal freeze-out interval (particle spectra, resonances and particle yields, multi-strange baryons spectra, HBT correlations)
John Harris (Yale University) QCD@Work 2003, Bari, Italy
From the Quark-Gluon Quagmire Emerges Hard Scattering
hadrons
leading particle
hadrons
leading particle
New for heavy ion physics Hard Parton Scattering sNN = 200 GeV at RHIC (vs 17 GeV at SPS)
Jets and mini-jets 30 - 50 % of particle production
high pt leading particles (jets?) azimuthal correlations
Scattered partons propagateradiate energy (~ few GeV/fm) in colored medium
suppression of high pt particles
alter di-jets and azimuthal correlations
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Hadron Spectra: Comparison of AA to NN
Nuclear Modification Factor RAA:AA = Nucleus-NucleusNN = Nucleon-Nucleon
ddpdT
ddpNdpR
TNN
AA
TAA
TAA /
/)(
2
2
Nuclear overlap integral:# binary NN collisions / inelastic NN cross section
NN cross section
AA cross section
AA
(pQCD)
Suppression:Parton energy loss R < 1 at large Pt
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Comparison: pA and Pb+Pb to p+p at Lower s
SPS: If any parton energy loss, it is overwhelmed by initial state soft multiple scattering(Cronin effect)
Transverse Momentum (GeV/c)
RAA
CERN SPS Ions – central collisions tppA ppA FNAL fixed target
Initial state soft multiple scattering (Cronin effect)
R = 1QCD
R > 1nuclear effects(Cronin)
RHIC: RAA < 1 for central Au+Au
K. Adcox et al. , Phys. Rev. Lett. 88, 022301 (2002)
C. Adler et al. , Phys. Rev. Lett. 89, 202301 (2002)
rati
o o
f c
entr
al A
A /s
cale
dp
pSuppression of Hadron Production Observed at RHIC
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Inclusive Hadron pt-spectra: s = 200 GeV AuAu
200 GeV results from all experiments
nucl-ex/0302015Submitted to Phys Lett B
nucl-ex/0305015 STAR PRL 89, 202301
Au-Au nucl-ex/0304022p+phep-ex/0304038
PHENIX
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Centrality dependence of RAA in Au+Au at s = 200 GeV
nucl-ex/0304022
nucl-ex/0305015
h+/-STAR
Au-Au nucl-ex/0304022
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Centrality dependence of RAA in Au+Au at s = 200 GeV
nucl-ex/0305015
h+/-STAR
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Particle Species Dependence of RCP (central/peripheral)in Au+Au at s = 200 GeV
• 1.5<pT<3.5 GeV/c: baryons not suppressed p, scales ~ Nbinary
0, K
0
s suppressed
• by pT ~ 6 GeV/c: , K0s, charged hadrons scale similarly
• explanations?
Partonic flow? Quark recombination? Modified fragmentation? Cronin effect?
preliminaryAu+Au
STAR
John Harris (Yale University) PANIC02, Osaka, Japan
Jets at RHIC?
Jet event in eecollision STAR p + p jet event
Can we see jets in high energy Au+Au?
STAR Au+Au (jet?) event
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Hard Scattering: Two-Particle Azimuthal Correlations
Technique:
Azimuthal correlation function
Trigger particle
pT > 4 GeV/c
Associate tracks
2 < pT < pT(trigger)
STAR
C2 () 1
N trigger
1
efficiencyd()N ( ,)
di-jets from p + p at 200 GeV
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Using p+p Di-jets to Study Central Au+Au Jets -Away-side Jet Disappears
Assume:high pT triggered Au+Au event
is a superposition:high pT triggered p+p event +
elliptic flow of AuAu event
C2(Au Au) C2(p p) A*(1 2v22 cos(2))
– v2 from reaction plane analysis
– A from fit in non-jet region (0.75 < || < 2.24)
Peripheral Au + Au
Away-side jet
Central Au + Au
disappears
John Harris (Yale University) QCD@Work 2003, Bari, Italy
High Pt Particle Suppression Jet Suppression
STAR Preliminary
Hadron suppression disappearance of back-to-back ‘jet’!
STAR PRL 90, 082302
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Experiment Confronts Theory
STAR nucl-ex/0305015 pQCD-I: Wang, nucl-th/0305010pQCD-II: Vitev and Gyulassy, PRL 89, 252301Saturation: KLM, Phys Lett B561, 93
pT > 5 GeV/c data described by saturation model (up to 60% central) and pQCD + jet quenching
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Disentangling Initial and Final State Effects at RHIC!
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
I. Vitev & M. Gyulassy, Phys.Rev.Lett. 89 (2002) pQCD + jet-quenching
Effect of “Cronin” and nuclear shadowing
Measure d+Au (for initial state effects) compare to p+p and Au+Au
+ quenching
SPS: Cronin dominantRHIC: Cronin, shadow, quench (dNg/dy)
RAA “flat”
John Harris (Yale University) QCD@Work 2003, Bari, Italy
No Suppression Observed in d + Au at RHIC!
PHOBOS Preliminary h±
h±
o
PHENIX Preliminary
STAR
Preliminary h±
John Harris (Yale University) QCD@Work 2003, Bari, Italy
No Suppression Observed in d + Au at RHIC!
STAR
Preliminary h±
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Comparing p + p, d + Au and Au + Au Jets
d + Au di-jets ~ p + p di-jetsvs
disappearance of central Au + Au away-side jet
STAR preliminary
John Harris (Yale University) QCD@Work 2003, Bari, Italy
High Pt Summary
Hadron spectra (vs binary scaling) High Pt hadrons suppressed in central Au + Au enhanced in d + AuBack-to-back Jets Di-jets in p + p, d + Au
(all centralities) Away-side jets quenched
in central Au + Au emission from surface
x
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Future at RHIC – Hard Probes
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
Charmonium (cc suppression/enhancement)- PHENIX start
Open Charm (charm production rates) – PHENIX recent PRLPHENIX - K. Adcox et al., Phys. Rev. Lett. 88, 192303 (2002)
Higher Pt triggers, jets fix parton energy loss (theory…)
Quantitative answers to questions on properties
Polarized pp measurements up to s = 500 GeV
(gluon and sea-quark contribution to proton spin)
Direct Photon Radiation?
New phenomena…….
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Thanks
K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002)
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
STAR, PHENIX, BRAHMS, PHOBOS CollaborationsRHIC Operations Group
for contributions and/or discussions:W. BuszaA. DreesM. GyulassyD. HardtkeP. JacobsM. MillerT. UllrichF. VidebaekX.N. WangW. Zajc
And all others I forgot to mention
John Harris (Yale University) QCD@Work 2003, Bari, Italy
K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002)
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
End of Presentation
Extra Slides Follow
John Harris (Yale University) QCD@Work 2003, Bari, Italy
• How can we determine the parton’s energy loss?
Energy Loss of Scattered Partons in Dense Matter
• elastic scattering of partons dE/dx ~ 0.1 GeV/fm Bjorken (1983)
• nonlinear interaction of gluons dE/dx ~ few GeV/fm Baier et al (1998)
gluesR
BDMS vLC
E ~4
22
• nonlinear interaction of gluons in thin plasma Gyulassy et al (2001)
L
ELogrdCE jet
glueSRGLV 23 2
,
Linear dep. on gluon density
John Harris (Yale University) QCD@Work 2003, Bari, Italy
Do We Know the Energy Loss in Confined Matter?Wang and Wang, hep-ph/0202105
Modification of fragmentation in e-Nucleus scattering:
10 GeV quark: dE/dx ~ 0.5 GeV/fm
F. Arleo, hep-ph/0201066
x1
Drell-Yan production in -Nucleus:
50 GeV quark: dE/dx <0.2 GeV/fm
John Harris QCD@Work 2003, Bari, Italy
Suppression at RHIC: Data Confronts Theory
Properties of the Medium
Parton Energy Loss : dE/dx ≈ 0.25 GeV/fm (expanding)
dE/dx|eff
≈ 7 GeV/fm (static source)
~ 15 times that in cold Au nuclei
Opacities: <n> = L/≈ 3 – 4
Gluon densities: dNg/dy ~ 900
John Harris (Yale University) QCD@Work 2003, Bari, Italy
“High” Pt Summary - Exp vs Theory
Ivan Vitev, QM2002
Preliminary sNN = 200 GeV
Wang and Wang, hep-ph/0202105Observe: strong suppression of high Pt hadrons
Requires: dE/dx = 7.3 GeV/fm ~ 10-15 times cold matter
gluon densities dngluon/dy ~ 500 – 1000
Suppression: an initial state effect?
Gluon Saturation (color glass condensate)
Wavefunction of low x gluons overlap; the self-coupling gluons fuse, saturating the density of
gluons in the initial state. (gets Nch right!)
• Multiple elastic scatterings (Cronin effect) Wang, Kopeliovich, Levai, Accardi
• Nuclear shadowing
Gribov, Levin, Ryshkin, Mueller, Qiu, Kharzeev, McLerran, Venugopalan,
Balitsky, Kovchegov, Kovner, Iancu …
probe rest frame
r/ggg
dAu AuAuR R RdAu~ 0.5D.Kharzeev et al., hep-ph/0210033
1dAuR
decreases dAuR
Broaden pT :