New Experimental Results from RHIC
Mark D. Baker (BNL)
Current and Future Directions at RHIC August 6, 2002
Many thanks to: Thomas Ullrich, Sergei Voloshin, Thomas Peitzmann
Mark D. Baker
Organization
• Initial State• “Bulk” Matter• Boost (Non)-Invariance• “Jet quenching”
Or failure to scale with Ncoll...
• Opacity/Explosiveness
• High2002 pT puzzles
• Summary
Mark D. Baker
PRL 88 (2002) 022302
• Start with low entropy• Final state interactions just reshuffle
Multiplicity is a window on the initial state
s (GeV)
Mark D. Baker
RHIC: Nch at mid-rapidity
Consistency of RHIC resultsPHENIX: PC, STAR: TPC
PHOBOS: Si BRAHMS: Si & Scint.
A. Bazilevsky (PHENIX)
PHENIX & STARpreliminary
Ratio R(200/130):BRAHMS: 1.14 0.05PHENIX: 1.17 0.03PHOBOS: 1.14 0.05STAR: 1.19 (no sys. yet)
QM2002 summary slide (Ullrich)
Mark D. Baker
Nch: Centrality Dependence at RHIC (SPS)
_pp
PHOBOS Au+Au ||<1
19.6 GeVpreliminary
130 GeV
200 GeV
Au+Au
(preliminary)
M. Baker (PHOBOS)
Everything counts:• Nch|=0 described nicely by KN (hard + soft)• Nch scales with Npart
collpp
partpp
Nxn
Nnx
d
dN
2
)1(
QM2002 summary slide (Ullrich)
Mark D. Baker
Nch(sNN) – Universality of Total Multiplicity?
pQCD e+e- Calculation
)/exp( sBsch CAN
Total charged particle multiplicity / participant pair
Total particle multiplicity reflects the initial state?Note: Still interesting dynamics in the final state interactions!
(A. Mueller, 1983)
2/sseff
Same for all systems at same s(seff for pp)
Mark D. Baker
e+e- measures dN/dyT
(rapidity relative to“thrust” axis)
200 GeV
More detailed comparison of AA, ee
Mark D. Baker
Understanding “Bulk” MatterStudying Matter:
Global Observables Nch, ET, pT
, S, …
Particle Yields & Ratios Tch, B, S, …
Particle Spectra Tfo, flow, stopping, …
Correlations
… and all that in pp, pA, AA
STAR preliminary
99.5%
QM2002 summary slide (Ullrich)
Mark D. Baker
Statistical Model: First Look at AuAu @ 200 GeV
All 200 GeV data taken from QM talks:F. Wang (STAR)/G. Van Buren (STAR)/T. Chujo (PHENIX)/Ouerdane (BRAHMS)J. Lee (BRAHMS)/B. Wosiek (PHOBOS)New 130 GeV data are:C. Suire (STAR)/J. Castillo (STAR)
Predictions:phenomenologically: B ~ 1.3 GeV (1+s/4.5 GeV)-1
assume unified freeze-out condition: E/N ~ 1.1 GeV T
QM2002 summary slide (Ullrich)
Mark D. Baker
K-/K+ and p/p from AGS to RHICI. Bearden (BRAHMS)
Becattini caluclation usingstatistical model: T=170, s=1 (weak dependency)
vary B/T K+/K- andp/p
K- /K+=(p/p)1/4 is a empirical fit to the data points
KK driven by s
~ exp(2s/T)
p/p driven by B
~ exp(-2B/T)
s = s (B) since <S> = 0BUT: Holds for y 0 (BRAHMS y=3)
QM2002 summary slide (Ullrich)
Mark D. Baker
Radial flowM. Kaneta/N. Xu (STAR)
<pT> prediction with Tth
and <> obtained from blastwave fit (green line)
<pT> prediction for Tch = 170 MeV and <>=0pp no rescattering, no flowno thermal equilibrium
STAR
preliminaryF. Wang
Mark D. Baker
Identified Particle Spectra at RHIC @ 200 GeV
Feed-down matters !!!
BRAHMS: 10% centralPHOBOS: 10%PHENIX: 5%STAR: 5%
QM2002 summary slide (Ullrich)
Mark D. Baker
Elliptic Flow
V2
Normalized Multiplicity
Particle asymmetry
dN/d(R ) = N0 (1 + 2V1cos (R) + 2V2cos (2(R)) + ... )
midrapidity : || < 1.0
STAR
Mark D. Baker
Centrality dependence @ RHIC.
STAR
v2=0.05
130 GeV: 0.075< pt < 2.0 200 GeV: 0.150< pt < 2.04-part cumulants
200 GeV: 0.2< pt < 2.0
Preliminary
200 GeV: Preliminary
Note possible dependence on low pt cut
- Consistent results- At 200 GeV better pronounced decrease of v2 for the most peripheral collisions.
STARPreliminary
QM2002 summary slide (Voloshin)
Mark D. Baker
v2 vs pseudorapidity
Talk by S. Manly
PHOBOS: No boost invariance !
QM2002 summary slide (Voloshin)
Mark D. Baker
p + p inel.
UA5, Z.Phys.C33, 1 (1986)
dN
/d
Systematic errors not shown
19.6 GeV is preliminaryPHOBOS Au+Au
dN
ch/d/<
Np
art>
beamy
6% central
beamy
Growth of Limiting Fragmentation Region
Mark D. Baker
Interlude: Many ways to slice pz
FTTz xs
pymp2
sinhsinh:
Away from mid-rapidity:
epem Ty
T TT pmy ln
Rapidity: Generalized velocity
Pseudorapidity: ~y: easier to measure
Feynman x: scaled pz
Mark D. Baker
Rapidity dists.: Boost-Invariance at RHIC ?
M. Baker (PHOBOS)
D. Ouerdane (BRAHMS)
1cosh)/(
cosh)/(),( :Jacobian
22
mp
mpp
y
QM2002 summary slide (Ullrich)
Mark D. Baker
NEW: Rapidity dependence of ratios at RHICI. Bearden (BRAHMS)
BRAHMS 200 GeV
At mid-rapidity:Net-protons: dN/dy 7proton yield: dN/dy 29 ¾ of all protons from pair-production
QM2002 summary slide (Ullrich)
Mark D. Baker
Boost-Invariance at RHIC ?
Boost invariance only achieved in small region |y|<0.5
Thomas Ullrich,
QM2002
Mark D. Baker
Suppression of Hadron Production (130 GeV)
ratio of pT-spectra AA central / pp
RAA < 1 for central Au+Aureactions at RHIC (130 AGeV)
observed in neutral pions and charged hadrons (PHENIX and STAR)
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
RAA =1 for scaling with number of binary collisions
J.C. Dunlop et al. , Nucl. Phys. A 698, 515c (2002)
K. Adcox et al. , Phys. Rev. Lett. 88, 22301 (2002)
QM2002 summary slide (Peitzmann)
Mark D. Baker
Energy Dep. of pT-spectra in pp and AA
spectra in pp strong variation
with beam energy “flattening”
of spectra power law
influence of hard scattering
K. Reygers et al., Hirschegg 2002
spectra in AA little variation
with beam energy almost exponential
influence of thermal production?
QM2002 summary slide (Peitzmann)
Mark D. Baker
Preliminary sNN = 200 GeV
Preliminary sNN = 200 GeV
C. Jorgensen, BRAHMS Parallel Saturday
C. Roland, PHOBOS Parallel Saturday
J. Jia, PHENIX Parallel Saturday
J. Klay, STAR Parallel Saturday
200 GeV results from all experiments
Charged Hadron Spectra
QM2002 summary slide (Peitzmann)
Mark D. Baker
The 4 experiments
Thomas Peitzmann, QM2002
Mark D. Baker
Normalize by Npart/2. Divide by the value at Npart=65
PHOBOS Preliminary:
Au+Au 200 GeV
UA1 pp (200 GeV)
Participant scaling of AuAu vs. AuAu??
C. Roland, QM2002
S. Mioduszewski, QM2002
Mark D. Baker
Jet Evidence in Azimuthal Correlations at RHIC
near-side correlation of charged tracks (STAR)
trigger particle pT = 4-6 GeV/c
distribution for pT > 2 GeV/c
signature of jets
also seen in (0) triggered events (PHENIX)
trigger particle pT > 2.5 GeV/c
distribution for pT = 2-4 GeV/c
M. Chiu, PHENIX Parallel Saturday
QM2002 summary slide (Peitzmann)
Mark D. Baker
Counter-Jet Suppressionjet suppression measure as a function of centrality
trigger-jet little modification(?)
most trigger particles from jets!
counter-jet strong suppression
with increasing Npart jet quenching?
inconsistencies for smallertrigger momentum
to be investigated
D. Hardtke, STAR Plenary Tuesday
QM2002 summary slide (Peitzmann)
Mark D. Baker
Surface Emission?
Jets ~ Npart??
How about Ncoll / V ?Future measurements may clarify this...
Idea from X.N.Wang, QM2002
Mark D. Baker
Opaque expanding source would mean:
Heiselberg, Levy,.PRC 59 (1999) 2716
)/(2 Tpufv TT
Mark D. Baker
High pT v2 reaches geometric surface limitv 2
impact parameter (fm)
QM2002 (Voloshin)
E. Shuryak, nucl-th/0112042
QM2002 (Filimonov, STAR)
)/()cos(
;)sin(
max,
Rb
v
262
2
ααα
Mark D. Baker
Opaque, expanding source would mean:
2222222 2)()( xtso YXRR
)(outX
)(sideY
29.13
5)(
)(
spheres
shellhalfs
R
R
65.012
5)(
)(
sphereo
shellhalfo
R
R
Opaque Expanding
Rischke RIKEN workshop (2002): Such strong xt correlations probably require a lack of boost-invariance...
Mark D. Baker
kT dependence of Rout/Rside
A. EnikizonoQM2002
C.M. Kuo, QM2002 poster (PHOBOS) 200 GeV:
.)(25.009.016.1 syst @0.25 GeV/c
Mark D. Baker
p/
• Proton yield is comparable with pions @ 2 GeV in central collisions, less in peripheral
Central
p/
Peripheral
Tatsuya Chujo (PHENIX)
Mark D. Baker
High pT Puzzle I:
T. Sakaguchi, PHENIX Parallel Saturday
Important baryon and/or kaon contribution out to pT = 8 GeV/c?
S. Mioduszewski, PHENIX
Mark D. Baker
Adler et al., nucl-ex/0206006
High pT puzzle II:
Still flowing at pT = 8 GeV/c?
Mark D. Baker
Our state is extreme• Hot dense state
Freezeout temperature near theoretical transition High Energy Density
• Very black source. v2 ~pT and ~ maximum allowed from surface
HBT Ro/Rs
Approximate Npart scaling of high pT particles
• Explosive source. Radial flow at roughly the speed of sound HBT Ro/Rs
(Unlike 2-particle correlations)• Alternatively (or additionally):
Magic near-instantaneous freezeout Blast wave or Humanic model
• Puzzles left at high pT
Mark D. Baker
Oh, what one day can do...
CERN baseline (17.3 GeV) PHOBOS preliminary
& NA49PbPb* WA98 (0-5%)
PbPb* NA50 (0-5%)
PbPb* NA50 (5-10%)
PbPb EMU13 (0-9%)
PbPb NA49 (0-5%)
PbPb 17.3 GeV (0-5%)
AuAu 19.6 GeV (0-6%)
Mark D. Baker
Energy Density Estimate (Bj)
Latticec
Bj~ 5 GeV/fm3
Bj~ 25 GeV/fm3
02j
TB
1 1 d
c dy
E
R
formation time: 0.2 - 1 fm
PRL 87 (2001) 052301
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