1. Milestones at the PHENIX experiment at RHIC
Máté Csanád, Eötvös University Budapest
for the PHENIX collaboration
Milestone #1: High pt suppression
Milestone #2: The erfect fluid of quarks
Heavy flavour
Chiral dynamics
Further results

2. M. Csanád for PHENIX, Hadron 2007
BNL Facility
STAR
PHENIX
PHOBOS
BRAHMS
RHIC, lenght: 3.83 km
protons: Linac  Booster  AGS  RHIC
ions: Tandems  Booster  AGS  RHIC
M. Csanád for PHENIX, Hadron 2007

3. M. Csanád for PHENIX, Hadron 2007
The Plan circa 2000
Use RHIC’s unprecedented capabilities
Large √s →
Access to reliable pQCD probes
Clear separation of valence baryon number and glue
To provide definitive experimental evidence for/against Quark Gluon Plasma (QGP)
Polarized p+p collisions → proton spin structure!
Two small detectors, two large detectors
Complementary & overlapping capabilities
Small detectors: BRAHMS and PHOBOS
3-5 year lifetime
Large detectors: STAR and PHENIX
Major capital investments
Longer lifetimes
Potential for upgrades in response to discoveries
M. Csanád for PHENIX, Hadron 2007

4. M. Csanád for PHENIX, Hadron 2007
Since then …
Accelerator complex
22 GeV (Au, Cu, p)
56 GeV (Au)
62 GeV (Au, Cu, p)
130 GeV (Au)
200 GeV (Au, Cu, d, p)
410 GeV (p)
500 GeV (p)
Science
100 publications in Phys. Rev. Letters
Major discoveries
Future: RHIC-II and eRHIC
Key science questions identified
Accelerator and experimental upgrade program underway
M. Csanád for PHENIX, Hadron 2007

5. M. Csanád for PHENIX, Hadron 2007
Event geometry
In these complicated events, we have a posteriori control over the event geometry:
Degree of overlap, number of participants (Npart)
Orientation with respect to overlap (Reaction Plane)
Central Au+Au
Npart~300
Peripheral Au+Au
Npart~50
d+Au
p+p
Reaction Plane
M. Csanád for PHENIX, Hadron 2007

6. M. Csanád for PHENIX, Hadron 2007
PHENIX capabilities
Central arm, |y|<0.35, Δφ=π
Tracking: DC, PC and TEC
Calorimetry: PbGl and PbSc (EMCal)
Particle ID: RICH and TOF
Muon arms, 1.2<|y|<2.4, Δφ=2π
Tracking: 3 muon tracker
Identification 5 detection planes
Front absorber to stop hadrons
Global detectors
BBC, MVD
Centrality, vertex, reaction plane
Physics
Charged hadrons ( π±, K±, etc.)
Photons, direct or decay (→ η , π0)
Light mesons φ, ω and η
Single leptons → heavy flavor
Di-leptons → heavy flavor, J/Ψ
M. Csanád for PHENIX, Hadron 2007

7. M. Csanád for PHENIX, Hadron 2007
Detector upgrades
2006
Aerogel
Hadron-Blind Detector
Reaction Plane Detector
Time Of Flight West
Muon Piston Calorimeter
2007 – 2009
Silicon Vertex Tracker
2008 – 2011
Forward Vertex Tracker
Nose Cone Calorimeter
M. Csanád for PHENIX, Hadron 2007 7

8. The PHENIX Collaboration
M. Csanád for PHENIX, Hadron 2007

9. M. Csanád for PHENIX, Hadron 2007
A PHENIX event
M. Csanád for PHENIX, Hadron 2007

10. Run-7 Au+Au: major success!
+ Upgrades: RXNP, TOF-W, MPC, HBD
M. Csanád for PHENIX, Hadron 2007

11. Milestone #1: jet suppression
Nuclear modification factor:
Measured in Au+Au, reference: p+p
High pt particles suppressed!
Counter-probe: d+Au → Medium effect (not color gl. cond.)
2 PRL covers
Au+Au
d+Au
M. Csanád for PHENIX, Hadron 2007

12. Systematic suppression of π0
Enhanced
Phys.Rev.C76:034904,2007
Suppressed
Appr. constant for pT > 4 GeV/c for all centralities
PQM (Loizides) hep-ph/ : 6 ≤ q^ ≤ 24 GeV2/fm
GLV (Vitev) hep-ph/ : 1000 ≤ dNg/dy ≤ 2000
WHDG (Horowitz) nucl-th/ : 600 ≤ dNg/dy ≤ 1600
M. Csanád for PHENIX, Hadron 2007

13. Photons shine, Pions don’t
No direct photon suppression until 14 GeV
Decreasing trend at >14 GeV
Isospin, shadowing and energy loss, see F. Arleo, hep-ph/
Suppression of π0 stays nearly constant up to 20 GeV/c
Direct photons are not inhibited by hot/dense medium
M. Csanád for PHENIX, Hadron 2007

14. J/Ψ suppression in Au+Au
Phys. Rev. Lett. 98, (2007)
Even J/ Ψ suppressed!
beyond extrapolations from cold nuclear matter effects
RAA ~ 0.3 for central collisions
Larger suppression at |y|>1.2
M. Csanád for PHENIX, Hadron 2007

15. Milestone #2: The perfect fluid
Reaction plane Δφ
Momentum distribution axially symmetric?
Azimuthal angle w.r.t. reaction place
Elliptic flow v2: azimuthal asymmetry
Second Fourier coefficient
Measures collective behavior
Zero v2 for a rare gas
Hydrodynamic behavior: v2 > 0
nucl-th/
M. Csanád for PHENIX, Hadron 2007

16. M. Csanád for PHENIX, Hadron 2007
Top Story 2005
According to the American Institut of Physics the top physics story in 2005 was the discovery of the perfect liquid
M. Csanád for PHENIX, Hadron 2007

17. Perfect fluid of quarks
PHENIX Collaboration, Phys.Rev.Letters 98:162301, 2007
Relevant variable: not pt, but transverse kinetic energ KEt
Elliptic flow scales with number of constituent quarks!
Degrees of freedom: quarks?
M. Csanád for PHENIX, Hadron 2007

18. M. Csanád for PHENIX, Hadron 2007
Even d, D and Φ flow
Strange and even charm quarks participate in the flow
v2 for the φ follows that of other mesons
v2 for the d follows thatof other barions
v2 for the D follows that of other mesons
nucl-ex/
M. Csanád for PHENIX, Hadron 2007

19. M. Csanád for PHENIX, Hadron 2007
Heavy flavour
Electrons from heavy flavour measured
Even heavy flavour is suppressed
Even heavy flavour flows
Strong coupling of charm+bottom to the medium
Small charm+bottom relaxation time in medium and small viscosity
Phys. Rev. Lett. 98, (2007)
M. Csanád for PHENIX, Hadron 2007

20. Signal of chiral dynamics
arXiv: [nucl-ex]
Significant excess at mee< 1GeV/c in Au+Au
Not in p+p
Not in peripheral Au+Au
Present in central Au+Au
Enhancement of η’, η, ω?
M. Csanád for PHENIX, Hadron 2007

21. Restoration of chiral symmetry?
Prediction: mass of h’ decreases in hot and dense matter due to UA(1) symmetry restoration
Idea: measure l(mt) at low momenta!
Hot and dense matter:
Modified h’ mass 
Enhanced h’ production
Decay:
h’h+p+ +p- (p0+p++p−)+p++p−
with long lifetime
Average p pt: 138 MeV
More non interacting p’s at 138 MeV
l(mt) measures fraction of interacting p’s
Hole in l(mt)
PHENIX PRELIMINARY
nucl-ex/
M. Csanád for PHENIX, Hadron 2007

22. Three particle correlations
Two angles: ΔΦ and ΔΘ
Simulations: jet deflection and Mach structures
Data: compatible with Mach cone like structure
Underlying v2 contribution not subtracted yet
M. Csanád for PHENIX, Hadron 2007

23. 3D two-pion source imaging
A new technique successfully applied
Two-pion correlation functions ↔ source functions
Distribution of pair separation measured
Information on hadronization
In LCMS: expected elongation in out (x) direction
Excess: elongation on the x and z axis; why?
Model-dependent answer: Resonance decays and Δτ=2fm/c
PHENIX PRELIMINARY
M. Csanád for PHENIX, Hadron 2007

24. M. Csanád for PHENIX, Hadron 2007
Critical phenomena
Density correlations measured
Well described by Negative Binomial Distributions
Interpolating between Bose-Einstein and Poisson
Basic parameter k ↔ ξ ↔ susceptibility χω=0~|T-Tc|-1
Parameter ξ monotonical in temperature
Not at the critical point!
Local max. at Npart≈90
Critical phenomenon?
in Landau-Ginzberg
framework
M. Csanád for PHENIX, Hadron 2007

25. Summary and conclusions
High pt hadrons suppressed
→ strongly interacting matter
Even J/Ψ and heavy flavour, photons not
Flow effects observed, quark number scaling
→ perfect fluid of quarks
Scaling valid for π, K, D, φ, p, d
Even charm and bottom flow
Details being explored
Source geometry
Critical phenomena
M. Csanád for PHENIX, Hadron 2007

26. Thank you for your attention

27. System size dependence of π0 RAA
RAA is the same in Cu+Cu and Au+Au at equal Npart
M. Csanád for PHENIX, Hadron 2007

28. J/Ψ production in p+p collisions
Phys. Rev. Lett. 98, (2007)
10 times more statistics than previous measurement
better constraints on rapidity and pt spectrum
better reference for the nuclear modification factor
M. Csanád for PHENIX, Hadron 2007

29. M. Csanád for PHENIX, Hadron 2007
J/Ψ RAA vs pT in Au+Au
Phys. Rev. Lett. 98, (2007)
No significant change of the pt distributions with respect to p+p, but error bars are large
M. Csanád for PHENIX, Hadron 2007

30. J/Ψ RAA vs rapidity in Au+Au
Phys. Rev. Lett. 98, (2007)
Peripheral:
no modification of the rapidity distribution with respect to p+p collisions
Central:
narrowing of the rapidity distribution
0-20%
20-40%
40-60%
60-92%
M. Csanád for PHENIX, Hadron 2007

31. M. Csanád for PHENIX, Hadron 2007
Viscosity
An AdS/CFT lower bound:
hep-th/ , gr-qc/ , hep-th/
Measurements
R. Lacey et al., nucl-ex/
H.-J. Drescher et al., arx:
S. Gavin, M. Abdel-Aziz, nucl-th/
A. Adare et al., nucl-ex/
M. Csanád for PHENIX, Hadron 2007

32. M. Csanád for PHENIX, Hadron 2007
A perfect fluid?
Perfect ≠ ideal!
Perfect: negligible viscosity and heat conduction
Ideal: incompressible
Viscosity h: measure of resistance to shear stress
Approx.:
Low viscosity  High cross-sect.  Strong coupling
Important measure: kinematic viscosity
AdS/CFT duality:
hep-th/ , gr-qc/ ,
hep-th/
Measurements:
nucl-ex/ , arxiv: ,
nucl-th/ , nucl-ex/
M. Csanád for PHENIX, Hadron 2007

33. Light mesons RAA High pt suppression for φ and ω, similar to π and η
, p and π in GeV 0-10%
ω in GeV, cent: 60-92% and 0-20%
High pt suppression for φ and ω, similar to π and η
RdA also compatible with (equal to 1)
M. Csanád for PHENIX, Hadron 2007

34. Comparison: ρ mass modification
calculations for min bias QGP, thermal radiation included
Broad range enhancement
150 < mee < 750 MeV 3.4±0.2(stat.) ±1.3(syst.)±0.7(model)
submitted to Phys. Rev. Lett
arXiv:
R.Rapp, Phys.Lett. B 473 (2000)
R.Rapp, Phys.Rev.C 63 (2001)
R.Rapp, nucl/th/
M. Csanád for PHENIX, Hadron 2007

35. M. Csanád for PHENIX, Hadron 2007
Mean pt2 vs Npart
<pt2>
0<pt<5 GeV/c
Constant vs Npart
For Au+Au, Cu+Cu, p+p
M. Csanád for PHENIX, Hadron 2007

36. 1st milestone: new phenomenon
Suppression of high pt particles: PHENIX result on the cover of Physical Review Letters
Is this a medium effect?
M. Csanád for PHENIX, Hadron 2007

37. M. Csanád for PHENIX, Hadron 2007
2nd: new type of matter
The new phenomenon is not obserable in d+Au collisions
Not the modification of the nucleus
Au+Au: it is a new type of matter!
M. Csanád for PHENIX, Hadron 2007

38. Proton spin structure via heavy flavor
Longitudinally polarized proton beams
J/Ψ measured
Sensitive to PDF
gluon
heavy fl.
gluon
proton
M. Csanád for PHENIX, Hadron 2007