Heavy Ion Caf

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Heavy Ion Café 1st meeting Experiment side

• K. Ozawa
• Univ. of Tokyo

2
Signatures of QGP
(1) Average transverse momentum (2) Volume (3)
Enhance of strangeness and charm (4) Enhance of
anti-particles (5) Elliptic flow (v2) (6)
Fluctuations conserved charges (7) Suppression of
high-pT hadrons (8) Heavy quarkonium (9)
Modification of light vector mesons (10) Thermal
photons and dileptons
(1)
(6)
(2)
(7)
(3)
(8)
(4)
(9)
(5)
(10)
K. Yagi, T. Hatsuda, and Y. Miake, Quark-Gluon
Plasma
3
In Reality
(1) Average transverse momentum (2) Volume (3)
Enhance of strangeness and charm (4) Enhance of
anti-particles (5) Elliptic flow (v2) (6)
Fluctuations conserved charges (7) Suppression of
high-pT hadrons (8) Heavy quarkonium (9)
Modification of light vector mesons (10) Thermal
photons and dileptons
pT spectrum HBT Heavy flavor Particle ratio
Elliptic flow Event-by-Event fluctuation Ratio
to expectation (RAA) J/y and Y light vector
mesons (r, w, f) Photons and electron pairs Near
and away side Jet
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Our activities and HI Cafe
pT spectrum HBT Heavy flavor Particle ratio
Elliptic flow Event-by-Event fluctuation Ratio
to expectation (RAA) J/y and Y light vector
mesons (r, w, f) Photons and electron pairs Near
and away side Jet
T. Chujo (M. Konno) A. Enokizono F. Kajihara and
S. Sakai M. Konno (T. Chujo) H. Masui and S.
Shimomura T. Nakamura T. Isobe T. Gunji and S.
Oda Y. Nakamiya (and K. Ozawa) K. Ozawa
???????????????????? ???????????????????
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Focus on Jet quenching

• At RHIC, we can use high pT particles to diagnose
  the medium.
• Measuring high pT particle yields
• Initial yields and pT distributions can be
  predicted from pp measurements pQCD cold
  nuclear effects
• Deviations can be attributed to the medium formed
  in AA collisions
• High pT particles (leading particles of jets) as
  p0, h can be measured in large BGs (dNch/dh 700)

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Observables

• Yield suppression by medium effects
• Comparison with pp
• Nuclear modification factor (RAA)

• Light (and Heavy) mesons
• Two (or three) particle correlation

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p0, h measurements
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The pp Reference

• Measurement at 200 GeV

• nucl-ex/0610036

h
p0
9
Initial State Effects?

• New PHENIX paper on centrality dependence of
  p0h in dAu at 200 GeV
• dAu as collision system to look for initial
  state effects

nucl-ex/0610036
gt no strong initial state effects
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AuAu at 200 GeV

• p0 data from RHIC run 2004

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RAA at 200 GeV
ltPeripheral to Central AuAu Collisiongt

• Stronger Suppression for more central collision.
• ?0 RAA is flat for all centrality for pTgt5 GeV/c.
  
• Difference between ?0 and charged increases for
  pT lt 5 GeV/c.

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AuAu at 200 GeV (h)

• h data from RHIC run 2004

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RAA at 200 GeV (h)

• h in AuAu

gt Suppression by a factor of 5 in central events
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RAA at 200 GeV

• Direct g, p0 and h in AuAu
• Direct g RAA with measured pp reference!

0-10 central events
gt RAA of h and p0 consistent, both show
suppression gt RAA of g is smaller than 1 at very
high pT
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RAA at Different Energies

• Comparison of p0 in CuCu at 200, 62.4, and 22.4
  GeV
• Measured the same collision species over a broad
  energy range
• Suppression gets larger with higher energies

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RAA at Different system size
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SPS and RHIC

• Same behavior for similar Npart (63 at WA98, 67.8
  at PHENIX)

Blattnig parameterization used for WA98 data (S.
Blattnig et. al., Phys.Rev. D62 (2000) 094030 /
D. DEnterria, Phys. Lett. B 596 (2004) 32))
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Summary I

• Strong suppression up to 20 GeV
• suppression patterns of p0 and h are similar
• Clear Collision Energy dependence
• Consistent results for the same system size and
  the same energy

Do these results mean jet energy loss in the
medium?
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Comparison with models
I. Vitev
C. Loizides hep-ph/0608133v2
Use RAA to extract medium density
W. Horowitz
I. Vitev 1000 lt dNg/dy lt 2000 W.
Horowitz 600 lt dNg/dy lt 1600 C. Loizides
6 lt lt 24 GeV2/fm
Statistical analysis to make optimal use of data
Caveat RAA folds geometry, energy loss and
fragmentation
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What do we learn from RAA?
GLV formalism
BDMPS formalism
15 GeV
Wicks et al, nucl-th/0512076v2
Renk, Eskola, hep-ph/0610059
DE15 GeV
Energy loss distributions very different for
BDMPS and GLV formalisms
But RAA similar!
Need more differential probes
21
RAA vs. Reaction Plane
AuAu collisions at 200GeV
nucl-ex/0611007
Out of Plane
In Plane
In plane emission shows no energy loss in
peripheral bins.
3ltpTlt5 GeV/c
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RAA Le Dependence
nucl-ex/0611007
AuAu collisions at 200GeV
Le matter thickness calculated in Glauber model
Little/no energy loss for Le lt 2 fm
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Heavy Flavor
pp reference Data (converter) for pTlt1.6
GeV/c 1.71FONLL for pTgt1.6 GeV/c
Suppression level is the almost same as p0 and h
in high pT region
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Summary II

• Several theoretical models can reproduce the
  experimental data.
• To investigate the origin of yield suppression,
  need more probes
• Reaction plane dependence of RAA is measured.
  Clear dependence on matter thickness is shown.
• Measurements for Heavy flavor show the similar
  results in high-pT.

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Two or Three particle correlation
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?? correlations at RHIC
?? correlations

• Trigger-associated technique valuable for
  tagging jets in high-multiplicity environment
  (vs. jet-cone algorithms)
• Probes the jets interaction with the QCD medium
• Provides stringent test of energy-loss models

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Dijet assoc. yields (IAA) vs. RAA
STAR, Phys. Rev. Lett. 91 (2003) 072304

• Near-side yields consistent with unity
• Away-side associated yields similar to RAA values

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Centrality dependence
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ZT Distribution

• Yield in ?fgt0.9
• ZT pT assoc/pTtrig

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IAA
IAA Yield(0-5 AuAu) Yield(dAu)
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Shape analysis
On this figure, Shape analysis is done.
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Away side peak shape

• 3 fitting functions are used.
• Shifted peak is at almost constant f.

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Jet Functions (PHENIX)
rms, kurtosis and D also independent of pT of
associated hadrons - poses challenge to color
Cerenkov models
nucl-ex/0611019
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Interpretations
Gluon radSudakov
Mach Cone/Shock wave
Cherenkov radiation
T. Renk, J. Ruppert
V. Koch, A. Majumder, X-N. Wang
A. Polosa, C. Salgado
Stöcker, Casseldery-Solana et al
Also Vitev, Phys. Lett. B630 (2005)
Or large kT from radial flow or energy loss
Fries, Armesto et al, Hwa
Many explanations possible, need more input to
conclude
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3-particle correlations
Event by event deflection of jets
Cone like structure in each event
??
??
??13
??13
?
?
0
?
??
0
?
??
??12
??12
1 3 lt pt lt 4 GeV/c (Jet Tag) 2,3 1 lt pt lt 2
GeV/c,
3-particle Dj-Dj probes away-side
structure Distinguish event-by-event deflection
vs conical (Mercedes) emission pattern
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Jet - Flow Subtraction Result
??13
??12
Diagonal and Off-diagonal structures are
suggestive of conical emission at an angle of
about 1.45 radians in central AuAu.
Centrality 0-12
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3-Particle Correlations
(3 particles from di-jet) (2 from dijet 1
other)
Df0
Dqp
PHENIX Preliminary
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Correlation Topologies
Normal Jet
(unmodified)
Df Azimuthal Section
Deflected Jet
PHENIX Simulation
(scattered jet axis)
Cone Jet
(medium excitation)
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Near-Side Modification
0-10 Central CuCu
0-20 Central AuAu
Trigger pT
IAA CYAA/CYPP
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Near side Dh-Df Correlations
Phys. Rev. C73 (2006) 064907
mid-central AuAu pt lt 2 GeV

• Near-side long range correlation in ??
• STAR, nucl-ex/0509030
• near side ridge

Dr/vrref
3ltpt,triggerlt4 GeV pt,assoc.gt2 GeV
AuAu 0-10 preliminary
0.8lt pt lt 4 GeV nucl-ex/0607003 See Poster by Ron
Longacre
3 lt pT(trig) lt 6 GeV2 lt pT(assoc) lt pT(trig)
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g-Jet Correlations
pp collisions at 200 GeV
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Comparison to Pythia
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g-Jet Correlations in AuAu
Poster M. Nguyen, N. Grau Talk J. Jin (2.2.07)
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Summary III

• We can see a clear away side suppression in two
  particle correlation.
• In addition, away side broadening exists.
• Analysis for three particle correlation is done.
  It suggests conical emission.