Transcript ppt - JINR

Heavy Ions Collisions
(results and questions)
PART II
Anatoly Litvinenko
[email protected]
1
Some estimations
ΔN =
dN
Δy = (900 - 1800)Δy;
dy
ΔV = πR 2 Δyτ Form ;
n(1 / fm 3 ) = ΔN / ΔV = (
dN
)/(πR 2 τ Form ) = (800 - 1600)/200 = (4 - 8)(1/fm 3 )
dy
λ = 1/nσ
σ = 30 mb ⇒λ = (0.07 - 0.035) fm
2
Particle ratios and statistical models
3
Particle (hadrons) spectra
A Iordanova (for the STAR Collaboration);J. Phys. G35, p.044008, (2008
4
elliptic flow hydrodynamics
:
elliptic flow and space eccentricity
A2 = v2 / ε
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.
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
KET – CQN Scaling
Baryons
Mesons
Phys. Rev. Lett. 98,
162301 (2007)
Quark-Like Degrees of Freedom Evident
Roy A. Lacey, Stony Brook; Quark Matter 09,
Knoxville, TN March 30 - April 4, 2009
10
Elliptic flow – energy dependance
K. Aamodt et al.(ALICE Collaboration), PRL 105, 252302 (2010)
11
JET Quenching
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.
1
 dP()
0
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 – 059 - 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
High pT (> ~2.0 GeV/c) hadrons in NN
h
d
h
Parton distribution functions
a
c
b
h
h
Hard-scattering
cross-section
Fragmentation Function
d ABhX   f A / a ( x a , Q a2 )  f B / b ( x b , Q b2 )  d ab  cd  Dh / d ( z d , Q d2 )
a ,b ,c,d
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
dσ AB→hX =
∑
a ,b , c ,d

N Coll f A / a (...)  f B / b (...)
z *d
 d P (  )
zd
0
1

D h / d ( z *d , Q d2 )

d ab  cd
Suppression of high-pt hadrons. Qualitatively.
Nuclear modification factor
dσ AA / < N coll >
R AA =
dσ NN
From naive picture
R AA
is what we get divided by what we expect.
15
Nuclear modification factor
dσ AA / < N coll >
R AA =
dσ NN
Normalization on peripheral collisions
(dσ AA / < N coll > )c
R CP =
(dσ AA / < N coll > )p
16
First data in first RHIC RUN
Jet Quenching ! Great!
But (see the next slide)
17
Nuclear modifications to hard scattering
d 2 N AA /dpT d
RAA ( pT ) 
TAA d 2 NN /dpT d
Large Cronin
effect at SPS

and ISR
Suppression at
RHIC
Is the suppression due to the medium?
(initial or final state effect?)
18
Centrality dependance
Again Au+Au and d+Au
Au+Au @ sNN = 200 GeV
d+Au @ sNN = 200 GeV
preliminary
• Nice picture! Isn’t it?
20
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 ;it is at partonic level
•  > 15 GeV/fm3; dNg/dy > 1100
21
JET Quenching at LHC
.ALICE Collaboration, Physics Letters B 696 (2011) 30
.
22
JET Quenching at LHC
ALICE Collaboration, Physics Letters B 696 (2011) 30
23
The matter is so dense that even heavy
quarks are stopped

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?
(1) q_hat = 0 GeV2/fm
(4) dNg / dy = 1000
(2) q_hat = 4 GeV2/fm
(3) q_hat = 14 GeV2/fm
24
If there are any other observables for Jet Quenching?
Yes! Back to Back Jets correlation.
Near side jet
Trigger particle

Associated particles
Away side jet
Correlation of
trigger particles
4<pT<6.5 GeV with
associated particles
2<pT<pT,trig
25
Back to Back Jets correlation.
Dependence from reaction plane.
Out-of-plane
In-plane
In-plane
Out-of-plane
26
Jet tomography
STAR Preliminry
20-60%
20-60%
Out-plane
Back-to-back suppression depends on
the reaction plane orientation
energy loss dependence
on the path length!
In-plane
27
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
Resonances melting
(Debye scrinig)
29
One more results from lattice QCD
heavy-quark screening mass
J/
(r ) ~ exp(  r ) / r
-- suppression
In EM plasma it is well known Debye screening
  1 / rD ~ 1 / T
30
The matter is so dense that it melts(?)
J/ (and regenerates it ?)
dAu

200 GeV/c
AuAu

200 GeV/c
CuCu

200 GeV/c
AuAu
ee
200 GeV/c
CuCu
ee
200 GeV/c
 J/’s are clearly
suppressed beyond
the cold nuclear
matter effect
 The preliminary data
are consistent with
the predicted
suppression + regeneration at the
energy density of
RHIC collisions.
 Can be tested by
v2(J/)?
31
The matter is so dense that it melts Y.
QM’11
direct photons
• T0max ~ 500-600 MeV !?
T0ave ~ 300-400 MeV !?
33
Summary
o RHIC has produced a strongly interacting,
partonic state of dense matter
 Bj  15 GeV / fm
3
34
Summary
o The matter is so dense that even
heavy quarks are stopped
(1) q_hat = 0 GeV2/fm
(4) dNg / dy = 1000
(2) q_hat = 4 GeV2/fm
(3) q_hat = 14 GeV2/fm
35
Summary
o The matter is so strongly coupled
that even heavy quarks flow
36
Summary
o The matter is so dense that it melts(?)
J/ (and regenerates it ?)
37
Summary
o The matter modifies jets
38
Put the results together
The matter is dense
The matter is
strongly coupled
 > 15 GeV/fm3
dNg/dy > 1100
Tave = 300 - 400 MeV (?)
PHENIX preliminary
The matter
modifies jets
The matter may melt
but regenerate J/’s
39
The matter is hot
Backup slides
40
CGC
CGC
CGC
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
January 6,
2002
RHIC/INT Winter
Workshopproper
2002
Instantaneous
freeze-out
at constant
time (“sharp”)
45
N Coll
z *d
f A / a (...)  f B / b (...)  d ab  cd  dP( )  Dh / d ( z *d , Q d2 )
zd
0
a ,b ,c ,d
∑
1
∑f A / a (...)  fB / b (...)  d ab  cd  D
a ,b ,c ,d
h/d
( z d , Q2d )
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
The QGP in the early universe
50
What kind of transition is predicted by lattice QCD
51
Dependence on pseudorapidity of charged hadron
S.S. Adler et al. , Phys. Rev. C 71, 034908 (2005)
52
Theoretical explanation
Estimation from data
Comparison to model calculations
with and without parton energy loss:
d ~ p T8 , and R AuAu ~ 0.2
p / p ~ 0.2
Numerical values range from
~ 0.1 GeV / fm (Bjorken,
elastic scattering of partons)
~several GeV / fm (BDMPS, nonlinear interactions of gluons)
Too many approaches.
We need additional data!
53
Initial state effects (test experiment d+Au)
h /
Suppression in central Au+Au due to final-state effects
54
Binary scaling. Is it work?
55
How about suppression for protons?
New
R CP  (dN / Ncoll )c /(dN / Ncoll )p
Close to nuclear mod. factor, because no suppression for peripheral coll.
56
Jets composition as measured by STAR
Kirill Filimonov, QM’04
57
58
Binary scaling. Is it work?
Au+Au 200 GeV/A: 10% most central collisions
( pQCD x Ncoll) /  background Vogelsang/CTEQ6
Preliminary
( pQCD x Ncoll) / ( background x Ncoll)
[w/ the real psuppression]
[if there were no psuppression]
[p]measured / [p]background =
pT (GeV/c)
measured/background
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, nonlinear interactions of gluons)
Too many approaches.
We need additional data!
60
If is there space for Color Glass Condensate or only Cronin Effect?
May be. Look at the BRAMS DATA
61
62
Observables and space time structure
of Heavy ion collisions
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
Observables and space time structure
of Heavy ion collisions
Production of semi-hard particles:
 gluons, light quarks
 relatively small momentum: pT  1 2 GeV / c
 make up for most of the multilplicity
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
Observables and space time structure
of Heavy ion collisions
Quark gluon plasma
67
Observables and space time structure
of Heavy ion collisions
Hot hadron gas
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
One more observable. Particle ratios
N/p ratio shows baryons enhanced for pT < 5 GeV/c
70