t. hallman ichep06 moscow july 31, 2006
DESCRIPTION
New Results and Future Perspectives in Relativistic Heavy Ion Physics. T. Hallman ICHEP06 Moscow July 31, 2006. Outline of this talk. Recent results from RHIC & SPS Hard Probes (R AA of heavy quarks, di-hadron correlations) Quarkonium Interplay of high p T partons with the medium - PowerPoint PPT PresentationTRANSCRIPT
Hallman: ICHEP06
T. HallmanICHEP06Moscow
July 31, 2006
New Results and Future Perspectives in Relativistic Heavy Ion Physics
Hallman: ICHEP06
Outline of this talk
– Recent results from RHIC & SPS• Hard Probes (RAA of heavy quarks, di-hadron correlations)
• Quarkonium
• Interplay of high pT partons with the medium
• Flow, global observables, etc.
– Search for QCD Critical point– On the eve of new discoveries at the LHC– Summary
Hallman: ICHEP06
1. Introduction:N. Armesto: ICHEP06
Hard Processes in Heavy Ion Collisions 3
Jet quenching/heating
Quarkonium suppression
Control of the benchmark:prompt photons anddileptons
● Hard processes (probes of the medium created in a HIC): those whosebenchmark (result of the probe in cold nuclear matter) is computable withinperturbative QCD, for which a hard scale is required (p
T, m
Q,...>>1/R
h).
● Strategy: no medium (pp) and cold nuclear matter (pA) understood inpQCD define the benchmark for the probe; results in hot medium (AB) andtheir difference with expectation provide a (pQCD or not) characterization.
Hallman: ICHEP06pQCD in p+p at RHIC
Good agreement with NLO pQCD pQCD should be broadly applicable at RHIC (e.g. heavy flavor production…)
Inclusive jets
Hallman: ICHEP06
By comparison, in central Au+Au collisions, jet quenching is observed:
hadrons are suppressed; direct photons (the control) are not as we expect
ddpdT
ddpNdpR
TNN
AA
TAA
TAA /
/)(
2
2
Binary collision scaling
p+pNuclear Modification Factor
sNN = 200
Hallman: ICHEP06
Heavy quark energy loss
• In vacuum, gluon radiation suppressed at < mQ/EQ
• “dead cone” effect: heavy quarks fragment hard into heavy mesons
QDokshitzer, Khoze, Troyan, JPG 17 (1991) 1602.Dokshitzer and Kharzeev, PLB 519 (2001) 199.
Dead cone also implies lower heavy quark energy loss in matter: (Dokshitzer-Kharzeev, 2001)
1
1
dd
d
d2
2
2
Q
Q
LIGHT
HEAVY
E
m
II
Up to QM05, a reasonably strong consensus that the suppression was basically understood: radiative energy loss in a medium 30-50 times normal nuclear matter density
Then these measurements were extended to the heavy quark sector (c, b) by studying suppression of electrons from their semi-leptonic decays
Hallman: ICHEP06Heavy flavor suppression via b,c e+X
Gluon density/qhat constrained by light quark supression+entropy density (multiplicity)
under-predicts electron suppression charm vs beauty? elastic energy loss? …?
RAA(non-photonic electrons) ~ 0.2 ~ RAA() !!
S.Wicks et al., nucl-th/0512076Armesto et al., Phys.Lett.B637:362-366,2006
Hallman: ICHEP06
Elastic (collisional) energy loss revisitedS.Wicks et al., nucl-th/0512076
Elastic E comparable to Radiative E – not negligible
Elastic E important even for light quarks revisit energy density estimates?
Hallman: ICHEP06
One possibility: maybe all the non-photonic electrons are from charm decays?
BDMPS: N. Armesto et al, nucl-ex/0511257
c+b, collisional+radiative
c only, collisional+radiative
DGLV: Wicks et al, nucl-ex/0512076
c+b, radiative only
Submitted to PRL, nucl-ex/0607012
Hallman: ICHEP06Another thing to understand: N. P. electrons in p+p at RHIC vs FONLL
~factor 2
CD
F, P
RL
91, 241804 (2003)
D0
FONLL
M. Cacciari, Hard Probes
State of the art: Fixed-Order Next-to-Leading Log
STAR, nucl-ex/0607012
Tevatron charm and beauty vs FONLL: OK
• RHIC n.p. electrons: factor 3-5 excess(!)• Large ambiguity in relative contribution of ce/be
need to resolve b and c explicitly
?
NB: Consistent data between multiple independent measurements; problem is comparison with theory
Hallman: ICHEP06
Resolution of non-photonic electron suppression puzzle needs
• experiment: explicit measurement of c vs b suppression
• theory: unified framework incorporating both elastic and radiative energy loss
The short summary:
Hallman: ICHEP06
Di-hadron correlations: recoiling jets are strongly modified due quenching
cos()
pTassoc > 0.15 GeV
STAR, Phys Rev Lett 95, 152301
4< pTtrig < 6 GeV
STAR, Phys Rev Lett 91, 072304
pTassoc > 2 GeV
trigger
recoil
?
Well established experimental observation
Hallman: ICHEP06What is new: di-hadron correlations at higher pT
Recoil jet clearly seen above background but at suppressed rate
trigger
recoil
?
pTtrigger>8 GeV/c
Yie
ld p
er tr
igge
r
STAR, nucl-ex/0604018
Armesto: ICHEP06
Hallman: ICHEP06Recoiling hadrons: details
No angular broadening
No modificationof fragmentation
Recoil rate is suppressed but jet features unmodified see only non-interacting jets?
D(z
T)
Recoiling hadron distribution
STAR, nucl-ex/0604018
Detailed dynamical calculations (see T. Renk, hep-ph/0602045) suggest 75% of observed recoils are due to non-interacting jets
c.f. Armesto: ICHEP06
Hallman: ICHEP06High PT Summary
Experiment • jet quenching is well-established: multiple strong effects• key open issue: how does the medium respond to E?• second generation of high precision measurements:
• heavy flavor, correlations, +jet• RHIC upgrades (topological charm reco), high luminosity (+jet)• LHC brings qualitatively new physics
Theory• qualitative but not yet quantitative understanding of jet quenching• significant uncertainties in
• underlying mechanism (elastic vs radiative)• heavy quark production• modeling of dynamical evolution
Hallman: ICHEP06
Conclusions:N. Armesto: ICHEP06
Hard Processes in Heavy Ion Collisions 16
● Hard processes in HIC have a twofold interest:
* Extension of pQCD to new domains: new theoretical tools, relation with other domains (hard QCD, high density QCD),...* Characterization of the produced medium.
● Together with v2 and the (anti)baryon to meson anomaly, they have been
key to establish the production of high density matter in HIC at RHIC.
● Lesson from RHIC: control experiments(pp, dAu) must be an integral part of theHIC program to get clear conclusions.
● LHC: large yields of hard processes willbe available: if problems are solved, thissubject will play a central role in theheavy ion program.
Hallman: ICHEP06
Quarkonia
Hallman: ICHEP06J/ production from p-A to Pb-Pb collisions
In S-U and peripheral Pb-Pb collisions, the data points follow this normal nuclear absorption, which scales with L, the length of nuclear matter crossed by the (pre-resonant) J/.
In central Pb-Pb collisions the L scaling is broken and an “anomalous suppression” sets in.
J/
L
Projectile
Target
The study of J/ production in p-A collisions at 200, 400 and 450 GeV, by NA3, NA38, NA50 and NA51, gives a “J/ absorption cross-section in normal nuclear matter” of 4.18 ± 0.35 mb.
J/ normal nuclear
absorption curve
S(J/) ~ exp(-L abs)NA38/NA50
450 GeV
400 GeV
200 GeV
extrap. to 158 GeV
Woehri: ICHEP06
Hallman: ICHEP06
Set A (lower ACM current)
• Combinatorial background (, K decays) from event mixing method (negligible)
• Mass shape of signal processes from MC (PYTHIA+GRV94LO pdf)
• Multi-step fit: a) DY (M>4.2 GeV), b) IMR (2.2<M<2.5 GeV), c) charmonia (2.9<M<4.2 GeV)
• Results from set A and B statistically compatible → use their average in the following
• Stability of the J/ / DY ratio:• change of input distributions in MC calculation → 0.3% (cos), 1% (rapidity)
• level of muon spectrometer target cut → < 3%
Set B (higher ACM current)
J/ / DY analysis
Woehri: ICHEP06
Hallman: ICHEP06
• Data points have been normalised to the expected J/ normal nuclear absorption, calculated with
as measured with p-A NA50 data
B. Alessandro et al., Eur. Phys. J. C39(2005) 335
J/abs = 4.18 0.35 mb
bin1 Npart = 63
bin2 Npart = 123
bin3 Npart = 175
3 centrality bins
• Qualitative agreement with NA50 results plotted as a function of Npart
Anomalous suppression present in Indium-Indium
J/ / DY vs. centrality
Woehri: ICHEP06
Hallman: ICHEP06
The J/ suppression patterns are in fair agreement when plotted versus Npart
Comparison with other SPS results
Woehri: ICHEP06
Hallman: ICHEP06
Npart
Mea
s/E
xp
1
Step position
A1A2
Step position: Npart = 82 ± 9
A1= 0.98 ± 0.03
A2= 0.85 ± 0.01
2/dof = 2.0
Resolution on Npart estimate (due to the measured EZDC resolution) taken into account
A certain amount of physics smearing can be accommodated by the data
Comparison with the extreme case of a step-like function
Woehri: ICHEP06
Hallman: ICHEP06
Sequential suppression:N. Armesto, ICHEP06
23
● In the last 5 years, lattice results and potential model calculations supporta sequential melting of quarkonium in the QGP.
● Sequential melting provides an alternative mechanism (others: comovers,percolation,...) to explain data (Karsch, Kharzeev, Satz '05): p
T broadening?
Hallman: ICHEP06
PHENIX PRL96 (2006) 012304
Proton-Proton at 200 GeV
(ppJ/) = 2.610.200.26b
RHIC Baseline MeasurementsDeuteron-Gold at 200 GeV
Consistent with 1-3 mb nuclear absorption and modest hint of
shadowing effect
Hallman: ICHEP06
Preliminary RHIC Gold-Gold Results
Sup
pres
sion
Fac
tor
Collision Centrality
Higher energy density at RHIC leads to prediction of greater suppression than at SPS.
Models over predict suppression. In fact, suppression is very similar to that found at the SPS (?): charm recombination, no J/ melting, only c? CuCu, AuAu J/ data as a function of centrality, rapidity and pT will hopefully settle these questions.
Arkhipkin, Armesto: ICHEP06
Hallman: ICHEP06
Interplay of high pT partons with the medium:
one of the most exciting questions
Hallman: ICHEP06
Medium response to jet energy loss ?
Au+Au 0-10%preliminary
3<pt,trigger<4 GeV
pt,assoc.>2 GeV
Armesto et al, nucl-ex/0405301
One example: near-side “ridge” correlated with jet trigger
Induced radiation dragged by longitudinally expanding fluid?
Hallman: ICHEP06
Another intriguing conjecture
Three-particle correlations which would show such effects (mach cone, Cherenkov gluons) are actively being pursued by STAR and PHENIX
Hallman: ICHEP06
Flow, Global Observables, etc.
Hallman: ICHEP06RHIC Initial Conditions: CGC
19.6 GeV 130 GeV 200 GeV
Charged hadron pseudo-rapidity
1) High number of Nch indicates initial high density;2) Mid-y, Nch Npart nuclear collisions are not incoherent;3) Saturation model works (Kharzeev et al)
Initial high parton density at RHICPRL 85, 3100 (00); 91, 052303 (03); 88, 22302(02); 91, 052303
(03)
PHOBOS Collaboration
Xu: ICHEP06
Hallman: ICHEP06
Yield Ratio Results
- The system is thermalized at RHIC.- Short-lived resonances show deviations. There is life after chemical freeze-out. RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184.
Thermalmodel fits
data
Tch = 163 ± 4 MeV
B = 24 ± 4 MeV
Xu: ICHEP06
pT-integrated particle yield ratios in central Au+Au collisions consistent with Grand Canonical Stat. distribution across u, d and s quark sectors (S = 1). Inferred Temp. consistent with Tcrit (LQCD) phase transition
Hallman: ICHEP06
2cos2 vx
y
p
patan
Anisotropic Flow
x
yz
px
py
Elliptic Flow in Heavy Ion Collisions
Peripheral Collisions
Hallman: ICHEP06
Comparison of elliptic flow and predictions of hydro potentially provide evidence for local thermalization and an EOS with a soft point
- Minimum bias data! At low pT, model result fits mass hierarchy well!- Details do not work, need more flow in the model!
P. H
uo
vi ne
n, p
r ivate
com
mu
nica
t i on
s, 20
04
Xu: ICHEP06
Hallman: ICHEP06
-mesons Flow: Partonic Flow
-mesons are very special:- they do not re-interact in hadronic environment
- they show strong collective flow - they are formed via coalescence with thermal s-quarks
STAR Preliminary: QM05, M. Lemont, S. Blyth Hwa and Yang, nucl-th/0602024; Chen et al., PRC73 (2006) 044903
STAR Preliminary
Xu: ICHEP06
Hallman: ICHEP06
Collectivity, Deconfinement at RHIC
- v2 of light hadrons and multi-strange hadrons - scaling by the number of constituent quarks
At RHIC: mT - NQ scaling
Partonic Collectivity
Deconfinement
PHENIX: PRL91, 182301(03) STAR: PRL92, 052302(04), 95, 122301(05) nucl-ex/0405022, QM05
S. Voloshin, NPA715, 379(03)Models: Greco et al, PRC68, 034904(03)Chen, Ko, nucl-th/0602025Nonaka et al. PLB583, 73(04)X. Dong, et al., Phys. Lett. B597, 328(04).….
i ii
Xu: ICHEP06
Hallman: ICHEP06
KEKETT/n scaling across collision centralities/n scaling across collision centralities
KET/n scaling observed across centralities
R. Lacey
Lacey: ICHEP06
Hallman: ICHEP06A remarkable scaling of the fine structure of
elliptic flow is observed at RHIC
At midrapidity v2 (pt,M,b,A)/n = F(KET/n)*ε(b,A) R. Lacey
Lacey: ICHEP06
Hallman: ICHEP06
v2{2}, v2{4}, non-flow, and flow fluctuations
* 2 21 2 2
* 1/ 22 1 2
* * 4 2 21 2 3 4 2 2
1/ 4* 2 * *2 1 2 1 2 3 4
;
{2}
2 2 2
{4} 2
iu u v u e
v u u
u u u u v v
v u u u u u u
Several reasons for v to fluctuate in a centrality bin:1) Variation in impact parameter in a centrality bin
(taken out in STAR results)2) Real flow fluctuations (due to fluctuations in the
initial conditions or in the system evolution)
2
* 22 2 2 22 1
2 2vv uu v vv v
22
22 2* * * 2 24 4
2 2 24 2 12
vv
v uu uuu u v vv
Different directions to resolve the problem:- Find methods which suppress / eliminates non-flow
- Add more equations assuming no new unknowns
- Estimate flow fluctuations by other means
2 equations, at least 3 unknowns: v, δ, σ
22 2 2; {2} /v v v
Correlations with large rapidity gaps
Subject of this talk
Non-flow Flow fluctuations
Non-flow (not related to the orientationof the reaction plane) correlations:- resonance decays- inter and intra jet corelations
Use equations for v2{n}, n>4
Voloshin: ICHEP06
Hallman: ICHEP06
Shown in black are resultsobtained by correlatingtwo random particles from Main TPC. Non-flow contribution can be largeand positive.
In blue are results forv2 in the Main TPC regionobtained from correlations (Forward*Main) and(East*West). These resultsare affected insignificantly by non-flow correlations.
Note: significantly largerrelative non-flow contribution in Cu+Cu case compared to Au+Au
v2 from (Forward TPC * Main TPC) correlations
| η | < 0.9 (Main TPC) -3.9 < η < -2.9 (FTPC East)
2.9 < η < 3.9 (FTPC West)
Voloshin: ICHEP06
Hallman: ICHEP06
Some next steps for flow studies
Disentangle fluctuations and correlations to measure <v2> and use the rapidity dependence of the v2 fluctuations to eliminate the uncertainty in the initial conditions (CGC or Glauber)
Understand non-flow at high pt to extract precise particle type dependence of intermediate and high pt v2
Study the systematics (pt, centrality and -/sNN dependence) of ncq scaling and phi or Omega v2. Do indications of a quark and gluon phase disappear anywhere?
Measure direct D meson v2
Hallman: ICHEP06Energy Dependence of Particle Production
PHENIX @ QM01Nucl. Phys. A698, 171 (2002).
dNch/dη ~ ln(√s)
PHENIXPRC 71, 034908 (2005)
dNch/dη = (½Npart·A)ln(√sNN/√s0)A = 0.74±0.01 √s0 = 1.48±0.02 GeV
LHC prediction based on data trend for 350 participants:
dNch/dη @ η=0: 1100Total Nch : 13000
PHOBOS PRL 91,52303 (2003)
Milov: ICHEP06
Hallman: ICHEP06
The QCD critical point search
Ejiri, et.al.Taylor Expansion
Fodor, KatzLattice Re-weighting
Gavai, GuptaB Lower Limit
B √sNN
———————————————————
180 MeV 25 GeV420 MeV 7.5 GeV725 MeV 4.5 GeV
———————————————————Cleymans, et.al. M. Stephanov: hep-ph/0402115
For B=0, lattice QCD predicts a smooth crossover between hadrons and quark-gluon plasma at Tc=190 MeV
For B>0, lattice calculations are less reliable: predictions for location of the critical point are highly uncertain
Hallman: ICHEP06NUCLOTRON JINRProject parameters: maximum energy
5 GeV/nucl. for nuclei with А ~ 200.Upgraded Nuclotron: up to 10 GeV/nucl.
Sissakian, Sorin, Toneev: ICHEP06
Hallman: ICHEP06
1. A study of the phase diagram in the domain populated by heavy-ion collisions with the bombarding energy ~ 5 ÷ 10 GeV/nucleon to search
for the mixed phase seems to be a very attractive task.
2. The use of the isospin asymmetry as an additional conserving parameter to characterize the created hot and dense system attracts new interest in this problem (critical end-boundary hypersurface ? ).
3. The available theoretical predictions are strongly model dependent giving rather dispersive results. There are no lattice QCD predictions for this highly nonpertubative region. Much theoretical work should be done and only future experiments may disentangle these models.
4. A JINR Nuclotron possibility of accelerating heavy ions to the project energy of 5A GeV and increasing it up to 10A GeV can be realized in two-three years. This will enable us to effort a unique opportunity for scanning heavy-ion interactions in energy, centrality and isospin asymmetry. It seems to be optimal to have the gold and uranium beams in order to scan in isospin asymmetry in both central and semi-central collisions at not so high temperatures.
Conclusions
Sissakian, Sorin Toneev: ICHEP06
Hallman: ICHEP06
Large Heavy-ion Collider (LHC)
Hallman: ICHEP06Solenoid magnet 0.5 T Cosmic-ray trigger
PHOS
HMPID
Central tracking system• ITS • TPC• TRD• TOF
Dipole MagnetForward detectors
• FMD, T0, V0, ZDC• PMD
• absorbers• trigger chambers
Tracking Stations
Muon Spectrometer
The ALICE Detector Safarik: ICHEP06
Hallman: ICHEP06
ALICE PID • , K, p identified in large acceptance (2 * 1.8 units ) via a combination of dE/dx in Si and TPC and TOF from ~100 MeV to 2 (p/K) - 3.5 (K/p) GeV/c•Electrons identified from 100 MeV/c to 100 GeV/c (with varying efficiency) combining Si+TPC+TOF with a dedicated TRD •In small acceptance HMPID extends PID to ~5 GeV •Photons measured with high resolution in PHOS, counting in PMD, and in EMC
0 1 2 3 4 5 p (GeV/c)
1 10 100 p (GeV/c)
TRD e / PHOS /
TPC + ITS (dE/dx)
/K
/K
/K
K/p
K/p
K/p
e /
e /
HMPID (RICH)
TOF
Alice uses ~all known techniques!
Safarik: ICHEP06
Hallman: ICHEP06
Hadronic charmCombine ALICE tracking + secondary vertex finding capabilities (d0~60m@1GeV/c pT) + large acceptance PID to detect processes as D0K-+
~1 in acceptance / central event ~0.001/central event accepted after reconstruction and all cuts
S/B+S ~ 37
S/B+S ~ 8for 1<pT<2 GeV/c(~12 if K ID required)
significance vs pTResults for 107 PbPb ev. (~ 1/2 a run)
Safarik: ICHEP06
Hallman: ICHEP06
PDFsm RFc ,,,
00
PDFsm RFc ,,,
00
s = 14 TeV
Charm in pp (D0 → K) Sensitivity to NLO pQCD params
down to pt ~ 0 !
Safarik: ICHEP06
Hallman: ICHEP06
0 1 2 10 100
pt (GeV/c)
Bulk propertiesHard processes
Modified by the medium
ALICE
CMS&ATLAS
LHC Experiments
PID
T=QCD Qs
Single particle spectraCorrelation studies
Jet reconstruction
Safarik: ICHEP06
Hallman: ICHEP06
1.1 CMS detector
Si tracker with pixels | | < 2.4 good efficiency and low fake rates for pt > 1 GeV, excellent momentum resolution, p: pt/pt < 2%
Muon chambers || < 2.4 Fine grained high resolution calorimetry (HCAL, ECAL, HF) with hermetic coverage up to || < 5
TOTEM (5.3 η 6.7) CASTOR (5.2 < || < 6.6) ZDC (z = ±140 m, 8.3 ||)
B = 4 T
Fully functional at highest multiplicities; high rate capability for (pp, pA, AA), DAQ and HLT capable of selecting HI events in real time
CASTOR ZDCTOTEM
5.2 << 6.6 8.3 <5.3 << 6.7
Sarycheva: ICHEP06
Hallman: ICHEP06
2.3 J/ and spectra for multiplicity dNch/d = 2500
For Pb-Pb at integrated luminosity 0.5 nb-1
/K decays into b,c-hadrons into
S/B N
J/ 1.2 180000
0.12 25000
Combinatorial background: Mixed sources, i.e. 1 from /K + 1 from J/ 1 from b/c + 1 from /KSarycheva, Kodolova: ICHEP06
Hallman: ICHEP06
2.4 J/ and spectra
(subtraction of the like sign spectra)
both
muons
|| < 2.4
both
muons
|| < 0.8
both
muons
|| < 2.4
both
muons
|| < 0.8
See talk of Olga Kodolova for details.See talk of Olga Kodolova for details.
Sarycheva, Kodolova: ICHEP06
Hallman: ICHEP06
Channel Time = 1.2 106 s,
AA = A2pp, A = 208 (Pb) (Pythia6.2, CTEQ5M)
jet+jet, ETjet > 100 GeV 4 106
jet tagged by h,0, ET
jet > 100 GeV,
zh,0 > 0.5
2 105
B-jet tagged by ,
ETjet > 100 GeV, z > 0.3
ETjet > 50 GeV, z > 0.3
700
2 104
3.1 Jet cross section & expected event rate
Expected statistics for CMS acceptance(no trigger and reconstruction efficiency)
jet,| < 3, |h,| < 2.4
CERN Yellow Report, hep-ph/0310274
Sarycheva: ICHEP06
Hallman: ICHEP06
6.1 Summary and outlook
• At LHC a new regime of heavy ion physics will be reached where hard particle production can dominate over soft events, while the initial gluon densities are much higher than at RHIC, implying stronger partonic energy loss observable in new channels.
• CMS is an excellent device for the study of quark-gluon plasma by hard probes: - Quarkonia and heavy quarks - Jets, ''jet quenching'' in various physics channels • CMS will also study global event characteristics: - Centrality, Multiplicity - Correlation and Energy Flow reaching very low pT
• CMS is preparing to take advantage of its capabilities - Excellent rapidity and azimuthal coverage, high resolution
- Large acceptance, nearly hermetic fine granularity hadronic and electromagnetic calorimetry - Excellent muon and tracking systems - New High Level Trigger algorithms specific for A+A
- Zero Degree Calorimeter, CASTOR and TOTEM will be important additions extending to forward physics
Sarycheva: ICHEP06
Hallman: ICHEP06
For completeness…
Hallman: ICHEP06
Hallman: ICHEP06
Hallman: ICHEP06
Hallman: ICHEP06
Novel aspects of heavy ions at CERN:
• Probe initial partonic state in a novel Bjorken-x range
(10-3 – 10-5) :– nuclear shadowing,– high-density saturated
gluon distribution (CGC)– effectively moves RHIC
forward region to mid-rapidity at LHC
• Larger saturation scale (QS=0.2A1/6√s= 2.7 GeV) particle production dominated by the saturation region
Qualitatively new regime
J/ψ
ALICE PPR CERN/LHCC 2003-049
10-6 10-4 10-2 100
x
108
106
104
102
100
M2 (
Ge
V2)
10 GeV
Safarik: ICHEP06
Hallman: ICHEP06
Already a glimpse of saturation (TBC) in d+Au at RHIC
Cronin enhancement Cronin enhancement suppression suppression
I. Arsene et al., BRAHMS PRL 93 (2004) 242303.
Staszel: ICHEP06 See also talk by B. Gay Ducati
Hallman: ICHEP06
The heavy ion session covered all the above,
Plus other important experimental topics that could not be covered in the summary due to time:
– Ultra-peripheral heavy ion collisions (Timoshenko, Emel’yanov)
– Femptoscopic Correlations in Heavy Ion Collisions (Lednicky)
– Scale Dependent Analysis Approach for STAR AuAu Collisions (Rogachevsky)
Hallman: ICHEP06
Conclusions• It is unequivocal that a new form of dense matter is produced at
RHIC (jet quenching, v2, (anti) baryon / meson anomaly)– The data have led to new intriguing questions
• Strong suppression of NPE’s for open charm & bottom ( c,b quark abundances or collisional vs radiative energy loss?)
• How much influence does recombination/feed-down have for J/Psi yields at RHIC. Why does the apparent suppression seem so similar to the SPS where the energy density is lower?
• How much elliptic flow is the result of the initial-state conditions (CGC)?• Do we see other effects predicted by the CGC?• What is the full significance of observed NCQ scaling for bulk hadronic properties
– Probing this new matter in detail is going to be extremely exciting (Cherenkov gluons, jet tomography…)
Such questions are the focus of ongoing RHIC upgrades which are beginning to come on line
Other exciting new horizons are now within view (QCD critical point search, start-up of the heavy ion program at the LHC
The comparison of the sQGP at RHIC and the matter produced in heavy ions collisions at the LHC will provide a watershed of new insight
Hallman: ICHEP06
Backup Slides
Hallman: ICHEP06Radiative energy loss in QCD
CS
coherent
LPM Nq
dzd
dI
ldzd
dI ˆHeitlerBethe
2ˆ~ˆ~ LqLqdzd
dIddzE SCS
LPML
med
C
cformation Lt
BDMPS approximation: multiple soft collisions in a medium of static color charges
E independent of parton energy (finite kinematics E~log(E))E L2 due to interference effects (expanding medium E~L)
Medium-induced gluon radiation spectrum:
Total medium-induced energy loss:
2
2
22ˆ
qd
dqqdq mediumTransport coefficient:
Baier, Schiff and Zakharov, AnnRevNuclPartSci 50, 37 (2000)
Hallman: ICHEP06
Extracting qhat from hadron suppression data
RAA: qhat~5-15 GeV2/fm
Hallman: ICHEP06
Inclusive hadrons and surface bias
?
Inclusive measurementsinsensitive to opacity of bulk
Eskola et al., hep-ph/0406319
RAA~0.2-0.3 for broad range of q̂
Large energy loss opaque core
More differential observables are needed to probe deeper…
Hallman: ICHEP06
b vs c suppression
pT~5 GeV/c: ce suppression ~0.2 puzzle resolved if c e dominates non-photonic electron spectrum - is that permissible?
S.Wicks et al., nucl-th/0512076RAA
Hallman: ICHEP06
STAR preliminary
T. Renk, hep-ph/0602045
High pT dihadrons: detailed dynamical calculation
Trigger direction
Different geometrical biases underly trigger and recoil distributions
~75% of recoils due to non-interacting jets
All bremsstrahlung models: discrete term
Hallman: ICHEP06
Light hadrons:N. Armesto
Hard Processes in Heavy Ion Collisions: 3. Jet quenching 70
pT
parton>5 GeV
Detailed modeling of geometry.(Quark Matter 05)
Dainese, talk at PANIC05
D'Enterria '05Dainese et al '04
Hallman: ICHEP06
Recombination:N. Armesto ICHEP06
71
● At RHIC/LHC, ~ 10/100 ccbar pairs per collision: regeneration?
● To be tested by rapidity distributions, pT broadening, LHC?
Hallman: ICHEP06
• Event selection: 1-2%
• Input to Glauber model (Indium density distributions)
• Link EZDC – Npart
• Error on scaling J/pp from 450 to 158 GeV: 8% (centrality independent)
• Error on abs: 3–4 % (almost centrality independent)
• Error due to the J// DY normalization: ~ 6% (centrality independent)
>10% for EZDC < 3 TeV,negligible elsewhere
5–10 % for EZDC < 3 TeVnegligible elsewhere
Various sources of systematic errors have been investigated; their effects on the measured suppression pattern are:
• The most central bin is affected by a sizeable systematic error relatively to the others
• There is a ~10% systematic error, independent on centrality
Summary on systematic errors
We can accurately evaluate the shape of the suppression pattern, but its absolute normalisation is more uncertain
Woehri: ICHEP06
Hallman: ICHEP06
1.2 Forward Region Layout
|| > 3
(5.3 << 6.7)
TOTEM
Forward Forward HCalHCal
(3 << 5)
CASTOR (~ 10 λI)
(5.2 << 6.6)
ZDC
HADHADEMEM
(z = 140 m)
(8.3 <)
Hallman: ICHEP06
STAR capabilitiescorrelations
resi
dual
/re
f (G
eV
/c)2
STAR and NA49 K/ fluctuations
With 2 azimuthal coverage: STAR will excel at measurements of:
v1, v2, v4, for many particle-types (is and v2 from a QGP stage? does it go to zero at lower sNN?)correlations & fluctuations (is there a max. in fluctuations? what’s the signal source?)
Particle identification can be achieved over a broad pT range using:
TPC dE/dx, ToF, Topology, etc
Hallman: ICHEP06
εBJ=(Sτ)-1dET/dy √sNN = 200GeV (0%-5%) & τ =1fm/c 5.4 ± 0.6GeV/(fm2c)
What about “τ”? Limiting: τ = 1/(2Rγ) 0.15 fm/c Formation: τ = h/mT ≈ 0.6ET/Nch 0.3 fm/c
Bjorken Energy Density estimate
PHENIX PRC 71, 034908 (2005)
Milov: ICHEP06