1. (results and questions)
Heavy Ions Collisions
(results and questions)
PART II
12/27/2018
Anatoly Litvinenko 1
2008 A.Litvinenko

2. Some estimations 2

3. Particle ratios and statistical models3 3

4. Particle (hadrons) spectra
A Iordanova (for the STAR Collaboration);J. Phys. G35, p , (2008 4 4

6. elliptic flow hydrodynamics:

7. elliptic flow and space eccentricity

8. QUESTION II Is equilibrium state of hot and
dense hadronic matter achieved?
What is the conclusion about it
from experiment?
The strong indication that YES.

9. Observables and hadronic matter properties
Some designations
sQGP
for strongly-interacting Quark-Gluon Plasma
Commonly accepted:
QGP, pQGP,wQGP
for weakly-interacting Quark-Gluon Plasma

10. Quark-Like Degrees of Freedom Evident
KET – CQN Scaling
Phys. Rev. Lett. 98, (2007)
Mesons
Baryons
Quark-Like Degrees of Freedom Evident
Roy A. Lacey, Stony Brook; Quark Matter 09, Knoxville, TN March 30 - April 4, 2009 10 10

11. Elliptic flow – energy dependance
K. Aamodt et al.(ALICE Collaboration), PRL 105, (2010) 11 11

12. JET Quenching One of the possible observable
Jet: A localized collection of
hadrons which come from a fragmenting parton
Modification of Jet property in AA collisions, because of partons
propagating in colored matter, which lose energy.
One of the possible observable
Was predicted in a lot of works. Some of them (not all) are:
J.D.Bjorken (1982), Fermilab – PUB – 82 – THY.
M.Gyulassy and M.Palmer, Phys.Lett.,B243,432,1990.
X.-N.Wang, M.Gyulassy and M.Palmer, Phys.Rev.,D51,3436,1995.
R.Baier et al., Phys.Lett.,B243,432,1997.
R.Baier et al., Nucl.Phys.,A661,205,1999 12

13. High pT (> ~2.0 GeV/c) hadrons in NN
Parton distribution functions a b c
Hard-scattering
cross-section h h
Fragmentation Function

14. + High pT (> ~2.0 GeV/c) hadrons in AA
Parton distribution functions h
Hard-scattering
cross-section A B
Fragmentation Function +
Numbers of binary collisions
Partonic Energy Loss h

15. Suppression of high-pt hadrons. Qualitatively.
12/27/2018
Suppression of high-pt hadrons. Qualitatively.
Nuclear modification factor
From naive picture
is what we get divided by what we expect. 15 15
2008 A.Litvinenko 15

16. Nuclear modification factor
12/27/2018
Nuclear modification factor
Normalization on peripheral collisions 16 16
2008 A.Litvinenko 16

17. First data in first RHIC RUN
Jet Quenching ! Great!
But (see the next slide) 17

18. Nuclear modifications to hard scattering
Large Cronin
effect at SPS
and ISR
Suppression at RHIC
Is the suppression due to the medium?
(initial or final state effect?) 18

19. Centrality dependance

20. Again Au+Au and d+Au Nice picture! Isn’t it? Au+Au @ sNN = 200 GeV
sNN = 200 GeV
preliminary
sNN = 200 GeV
sNN = 200 GeV
preliminary
sNN = 200 GeV
sNN = 200 GeV
preliminary
sNN = 200 GeV
sNN = 200 GeV
preliminary
Nice picture! Isn’t it? 20

21. The matter is so opaque that even a 20 GeV p0 is stopped.
Suppression is very strong (RAA=0.2!) and flat up to 20 GeV/c
Common suppression for p0 and h; it is at partonic level
e > 15 GeV/fm3; dNg/dy > 1100 21

22. JET Quenching at LHC
.ALICE Collaboration, Physics Letters B 696 (2011) 30 .

23. JET Quenching at LHC
ALICE Collaboration, Physics Letters B 696 (2011) 30

24. The matter is so dense that even heavy quarks are stopped
(3) q_hat = 14 GeV2/fm
(2) q_hat = 4 GeV2/fm
(1) q_hat = 0 GeV2/fm
(4) dNg / dy = 1000
Even heavy quark (charm) suffers substantial energy loss in the matter
The data provides a strong constraint on the energy loss models.
The data suggest large c-quark-medium cross section; evidence for strongly coupled QGP? 24

25. Yes! Back to Back Jets correlation.
If there are any other observables for Jet Quenching?
Yes! Back to Back Jets correlation.
Near side jet
Trigger particle
Away side jet 
Associated particles
Correlation of
trigger particles 4<pT<6.5 GeV with associated particles 2<pT<pT,trig 25

26. Back to Back Jets correlation. Dependence from reaction plane.
Out-of-plane
In-plane
In-plane
Out-of-plane 26

27. Jet tomography Out-plane Back-to-back suppression depends on
20-60%
STAR Preliminry
Out-plane
Back-to-back suppression depends on
the reaction plane orientation
In-plane
energy loss dependence
on the path length! 27

28. The matter is so dense that it modifies the shape of jets
The shapes of jets are modified by the matter.
Mach cone?
Cerenkov?
Can the properties of the matter be measured from the shape?
Sound velocity
Di-electric constant
Di-jet tomography is a powerful tool to probe the matter 28

29. Resonances melting (Debye scrinig)29

30. One more results from lattice QCD
heavy-quark screening mass
-- suppression
In EM plasma it is well known Debye screening 30

31. The matter is so dense that it melts(?) J/y (and regenerates it ?)
J/y’s are clearly suppressed beyond the cold nuclear matter effect
The preliminary data are consistent with the predicted suppression + re-generation at the energy density of RHIC collisions.
Can be tested by v2(J/y)?
CuCu mm
200 GeV/c
AuAu
dAu ee 31

32. The matter is so dense that it melts Y.
QM’11

33. direct photons
T0max ~ MeV !?
T0ave ~ MeV !? 33 33

34. Summary RHIC has produced a strongly interacting,
partonic state of dense matter 34

35. The matter is so dense that even heavy quarks are stopped
Summary
The matter is so dense that even heavy quarks are stopped
(3) q_hat = 14 GeV2/fm
(2) q_hat = 4 GeV2/fm
(1) q_hat = 0 GeV2/fm
(4) dNg / dy = 1000 35

36. The matter is so strongly coupled that even heavy quarks flow
Summary
The matter is so strongly coupled
that even heavy quarks flow 36

37. The matter is so dense that it melts(?) J/y (and regenerates it ?)
Summary
The matter is so dense that it melts(?)
J/y (and regenerates it ?) 37

38. The matter modifies jets
Summary
The matter modifies jets 38

39. Put the results together
The matter is strongly coupled
The matter is dense
> 15 GeV/fm3
dNg/dy > 1100
Tave = MeV (?)
PHENIX preliminary
The matter modifies jets
The matter may melt but regenerate J/y’s 39 39
The matter is hot

40. Backup slides 40

42. CGC

43. CGC

44. CGC

45. RHIC/INT Winter Workshop 2002
Modeling the Source
Interaction region
Assembly of classical boson emitting sources in space-time region
The source S(x,p) is the probability boson with p is emitted from x
Determines single-particle momentum spectrum
E d3N/dp3 =  d4x S(x,p)
Determines the HBT two-particle correlation function C(K,q)
C(K,q) ~ 1 + |  d4x S(x,K) exp(iq·x) | 2/|  d4x S(x,K) |2
where K = ½(p1 + p2) = (KT, KL), q = p1 – p2
The LCMS frame is used (KL = 0)
In the hydrodynamics-based parameterizations: assume something about the source S(x,p)
Gaussian particle density distribution
Linear flow (rapidity or velocity) profile
Instantaneous freeze-out at constant proper time (“sharp”)
January 6, 2002
RHIC/INT Winter Workshop 2002 45

47. 48 48

48. Why the collisons of heavy nuclei is interesting?
Let us see on the space – time picture of collision
pre-collision
QGP (?) and parton production
hadron reinteraction
hadron production
QCD phase diagram 49 49

49. The QGP in the early universe50 50

50. What kind of transition is predicted by lattice QCD51 51

51. Dependence on pseudorapidity of charged hadron
S.S. Adler et al. , Phys. Rev. C 71, (2005)

52. Theoretical explanation
Comparison to model calculations
with and without parton energy loss:
Estimation from data
Numerical values range from
~ 0.1 GeV / fm (Bjorken,
elastic scattering of partons)
~several GeV / fm (BDMPS, non-linear interactions of gluons)
Too many approaches.
We need additional data! 53

53. Initial state effects (test experiment d+Au)
Suppression in central Au+Au due to final-state effects 54

54. Binary scaling. Is it work?55

55. How about suppression for protons?
New
Close to nuclear mod. factor, because no suppression for peripheral coll. 56

56. Jets composition as measured by STAR
Kirill Filimonov, QM’04 57

57. 58

58. Binary scaling. Is it work?
Au+Au 200 GeV/A: 10% most central collisions
Preliminary
[w/ the real suppression]
( pQCD x Ncoll) /  background Vogelsang/CTEQ6
[if there were no suppression]
( pQCD x Ncoll) / ( background x Ncoll)
pT (GeV/c)
[]measured / []background = measured/background 59

59. Theoretical explanation
Comparison to model calculations
with and without parton energy loss:
Numerical values range from
~ 0.1 GeV / fm (Bjorken,
elastic scattering of partons)
~several GeV / fm (BDMPS, non-linear interactions of gluons)
Too many approaches.
We need additional data! 60

60. If is there space for Color Glass Condensate or only Cronin Effect?
May be. Look at the BRAMS DATA 61

61. 62

62. Observables and space time structure of Heavy ion collisions63 63

63. Observables and space time structure of Heavy ion collisions
Production of hard particles:
jets
heavy quarks
direct photons
Calculable with the tools of perturbative QCD 64 64

64. Observables and space time structure of Heavy ion collisions
Production of semi-hard particles:
gluons, light quarks
relatively small momentum:
make up for most of the multilplicity 65 65

65. Observables and space time structure of Heavy ion collisions
Thermalization
experiment suggest a fast thermalization
(remember elliptic flow)
but this is still not undestood from QCD 66 66

66. Observables and space time structure of Heavy ion collisions
Quark gluon plasma 67 67

67. Observables and space time structure of Heavy ion collisions
Hot hadron gas 68 68

68. Particle ratio and statistical models
One assumes that particles are produced by a thermalized system with temperature T and baryon chemical potential
The number of particles of mass m per unit volume is :
These models reproduce the ratios of particle yields with only two parameters 69 69

69. One more observable. Particle ratios
12/27/2018
One more observable. Particle ratios
N/p ratio shows baryons enhanced for pT < 5 GeV/c 70 70
2008 A.Litvinenko 70