rhic: physics results
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Gunther Roland/MIT LHC 2003
RHIC: Physics Results
Gunther Roland
IV International Symposium on LHC Physics and Detectors
Fermilab 5/1-5/3 2003
Gunther Roland/MIT LHC 2003
Exploring QCD with Heavy Ions
Matter Density B (GeV)
I II III IV
Tem
per
atu
re (
MeV
)
Quark-Gluon Plasma
Hadron Gas
Phase Boundary
Early Universe
0
200
0
Atomic Nuclei
1
Critical Point
I
II
III
IV
1. Structure of Relativistic Nuclei
2. Mechanism of Entropy Production
3. QCD phase diagram
4. Properties of QGP
Gunther Roland/MIT LHC 2003
Interlude: Collision Geometry
b2R ~ 15fm
Spectators
Spectators
Participant Region
Smaller Impact Parameter b
Bigger Collision System
More Participants (Npart)
More Produced Particles!
Gunther Roland/MIT LHC 2003
Relativistic Heavy Ion Collider
First Physics in ‘00
Versatile machine – Au+Au (‘00-’02)
• 19.6 GeV
• 56 GeV
• 130 GeV
• 200 GeV
– p+p (‘02,’03)• 200 GeV
polarized
– d+Au (‘03)• 200 GeV• 4 Experiments
– 2 big– 2 small
• Complementary capabilities
Gunther Roland/MIT LHC 2003
STAR
• Large acceptance tracking detector• Mass, charge and momentum for >1000 hadrons
per event
Gunther Roland/MIT LHC 2003
PHENIX
• High Rate, Particle ID, Triggering
• Rare particles: Leptons, High pT
Gunther Roland/MIT LHC 2003
PHOBOS
• Full Acceptance Multiplicity Detector• High precision spectrometer near y=0 (low pT)
Gunther Roland/MIT LHC 2003
BRAHMS
• Particle Production at small angles
• High resolution spectrometer & good particle ID
Gunther Roland/MIT LHC 2003
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density
2. Thermalization
3. Hadro-Chemistry
4. Expansion Dynamics
Gunther Roland/MIT LHC 2003
4- Multiplicity at RHICd
N/d
Pseudo-rapidity
19.6 GeV 130 GeV 200 GeVPHOBOS PHOBOS PHOBOS
BRAHMS 130 GeV BRAHMS 200 GeV
dN
/d
Nice agreement!
PHOBOS nucl-ex/0210015
BRAHMS PLB 523 (2001) 227, PRL 88 (2002) 202301
Gunther Roland/MIT LHC 2003
Initially released energy density
~ 5GeV/fm3
Note: energy density inside proton ≈ 0. 5GeV/fm3
1=1−=
o45
1000~all
d
dN⎟⎟⎠
⎞⎜⎜⎝
⎛
GeVE 1~
32 200~)1(~ fmfmR
Total energy released ~2000GeVMax. initial overlap volume
Den
s ity
o
f P
arti
c le s
Pro
du
c ed
at
y=0
Energy of Collision
Energy DensityW. Busza, Moriond ‘03
Gunther Roland/MIT LHC 2003
Azimuthal Anisotropy
“Head on” view of colliding nuclei
Peripheral
Central
Initial State AnisotropyCoordinate Space
Final State AnisotropyMomentum Space
Interaction!
2*v2
Azimuthal Angle (rad)
Gunther Roland/MIT LHC 2003
Anisotropy v2 vs Centrality
STAR
|| < 1.3
0.1 < pt < 2.0
PHOBOS
PHENIX
from R. Snellings
Consistent results
Hydro-limit reached for
mid-central collisions
Gunther Roland/MIT LHC 2003
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density: > 5 GeV/fm3
2. Thermalization:
3. Hadro-Chemistry
4. Expansion Dynamics
Gunther Roland/MIT LHC 2003
Charged Particle Spectra
Results (largely) consistent
Clear Mass Hierarchy of Slopes
Th. Ullrich QM’02
Gunther Roland/MIT LHC 2003
Multi-Strange Particles
STAR Preliminary
J. Castillo SQM’03
Gunther Roland/MIT LHC 2003
Statistical Model Fit
Relative Abundance: Two Parameters !
Gunther Roland/MIT LHC 2003
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density: > 5 GeV/fm3
2. Thermalization:
3. Hadro-Chemistry: Tch ~ 180 MeV, B~25MeV
4. Expansion Dynamics
Gunther Roland/MIT LHC 2003
‘Hydro’ Fits to Spectra
Simultaneous Fit to ,k,p gives
Kinetic Freeze-Out Temperature,
Transverse Expansion velocity
Gunther Roland/MIT LHC 2003
‘Hydro’ Fit to Correlation Data
Fabrice Retiere SQM ‘03, Mike Lisa
Consistent Data from
STAR, PHENIX, PHOBOS
Also
HBT vs reaction plane
Unlike particles
Balance Functions
Short-lived Resonances
Consistent Results
Lifetime ~ 10 fm/c
Particle emission over
few fm/c
Gunther Roland/MIT LHC 2003
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density: > 5 GeV/fm3
2. Thermalization:
3. Hadrochemistry: Tch ~ 180 MeV, B~25MeV
4. Expansion Dynamics: Tth ~ 110 MeV, <T> ~ 0.6c
<fo>~ 10 fm/c, fo~ 0-3
fm/c
Gunther Roland/MIT LHC 2003
Bulk Particle Production @ RHIC
1. Initial Conditions/Energy Density: > 5 GeV/fm3
2. Thermalization:
3. Hadrochemistry: Tch ~ 180 MeV, B~25MeV
4. Expansion Dynamics: Tth ~ 110 MeV, <T> ~ 0.6c
<fo>~ 10 fm/c, fo~ 0-3
fm/c Consistent Description of Final State
But we’re missing a picture of Dynamical Evolution
Gunther Roland/MIT LHC 2003
II. Dense Matter Diagnostics @ RHIC
1. Jets
2. Virtual and Real Photons
3. Quarkonia
Gunther Roland/MIT LHC 2003
Dense Matter Diagnostics
Leading Particle
Hadrons
q
q
Hadrons
Leading Particle
Hadrons
q
q
Hadrons
Leading Particle
Jet cross-section calculable in QCD
Study fate of jets in dense matter in Au+Au
Leading Particle
Gunther Roland/MIT LHC 2003
STAR Au+AuOpal e+e-
Gunther Roland/MIT LHC 2003
Dense Matter Diagnostics
Leading Particle
Hadrons
q
q
Hadrons
Leading Particle
Hadrons
q
q
Hadrons
Leading Particle
Jet cross-section calculable in QCD
Study fate of jets in dense matter in Au+Au
Poor man’s jet: Leading Particles
Leading Particle
Gunther Roland/MIT LHC 2003
“Jet Quenching” at High pT
Yield at high pT in AA is 6 times smaller than expected
expected
observedproton+proton
Au+Au
Gunther Roland/MIT LHC 2003
Jets in Dense Matter
Are we really looking at jets?• Look for jet structure by
measuring– small angle correlations– back-to-back
correlations
relative to high pT leading particle
Hadrons
q
q
Hadrons
Leading Particle
Leading Particle
Gunther Roland/MIT LHC 2003
Peripheral Au+Au data
• Jets seen in peripheral Au+Au and p+p• Azimuthal correlations
– Small angle ( ~ 0)– Back-to-Back ( ~ p)
D. Hardtke
QM ‘02
Gunther Roland/MIT LHC 2003
Central Au+Au data
• Disappearance of back-to-back correlations in central Au+Au
• Away-side particles absorbed or scattered in medium
D. Hardtke
QM ‘02
Gunther Roland/MIT LHC 2003
“Instant” ThermalizationE. Shuryak, nucl-th/0112042
STAR
Central
Peripheral
High pT particlesproduced early:Biggest anisotropy
Limit (mfp = 0)
Gunther Roland/MIT LHC 2003
Thermalization timescale
• To fully preserve anisotropy:– Instant formation of dense system (mfp small)
• Why “instant”? Once washed out, anisotropy can’t be recovered!
timet=0
Gunther Roland/MIT LHC 2003
Anisotropy in Parton Cascade
HIJING x 80HIJING x 35HIJING x 13HIJING x 1hydro , sBC
Peripheral Central
0.06
0.1
0.02
An
iso
tro
py
Parton cascade can describe data…
…if cross-sections are multiplied by 13!
Molnar, Gyulassy
Gunther Roland/MIT LHC 2003
“Proton puzzle”
?
Gunther Roland/MIT LHC 2003
Understanding low vs high pT
Fries, Mueller, Nonaka,Bass nucl-th/0301087
Gunther Roland/MIT LHC 2003
III. RHIC in Context
Gunther Roland/MIT LHC 2003
(Mueller 1983)
)/exp( sAsch BN αα∝
Total Multiplicity vs. Beam EnergyPHOBOS QM’02, Steinberg
pp/pp
A+A
e+e-
Central A+A
<N
ch>
/e+e- F
it
Gunther Roland/MIT LHC 2003
Chemistry vs sqrt(s)Nucl. Phy. A697: 902-912 (2002)
Gunther Roland/MIT LHC 2003
Asymptotic region at RHIC?
pp/pp
A+A
e+e-Universality?
Energy
Hadronse+e-
What about strangeness?
Gunther Roland/MIT LHC 2003
Mid-Rapidity K/
Non-monotonic Evolution!
Oeschler et al: Thresholds vs Baryo-chemical potential
NA49 (V. Friese SQM’03)
Gunther Roland/MIT LHC 2003
Kaon Slope Parameters
NA49 (V. Friese SQM’03)
NA49NA49
AGS AGS
PHENIXPHENIX
Gunther Roland/MIT LHC 2003
Summary
• Extensive and Consistent Data Sets– BRAHMS, PHENIX, PHOBOS, STAR– AGS, SPS, RHIC
• Consistent and Concise description of Final State – Bulk particle production
– Intermediate pT spectra + correlations
• Challenge: Consistent Dynamical Scenario– What makes all this happen in 10fm/c?
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