Collectivity in the sQGP
Mike Lisa
Ohio State University
25 october 2006
DNP 2006, Nashville - mike lisa
1
Outline
• purpose / definition of soft physics
• results
• flow
• flow
• flow
• flow
• summary / outlook
25 october 2006
DNP 2006, Nashville - mike lisa
2
Outline
• purpose / definition of soft physics
• results
• flow - femtoscopy: space-mom. substructure
• flow - pT spectra
• flow - anisotropy (v2, v4)
• flow - open questions
• summary / outlook
25 october 2006
DNP 2006, Nashville - mike lisa
3
soft / firm / hard diagnostics
• hard (jets/leading particles)
• suppression / energy loss of
fast / heavy-flavor hadrons
• Jin / Ullrich / van Hees
• firm (away-side shape)
• thermalization of probe
• local effect of non-equilibrium
stimulus
• Jin / van Hees / Wang
• soft (global shape/yield)
• bulk collective behaviour
• equilibrium (?) response to
global stimulus
25 october 2006
DNP 2006, Nashville - mike lisa
4
Microexplosions
Femtoexplosions
1018 K/sec
1035 K/s
• energy quickly deposited
s
0.1 J
1 J
• enter plasma phase
1017 J/m3
5 GeV/fm3 = 1036 J/m3
• expand hydrodynamically
•Tcool back to10original
phase 200 MeV = 1012 K
6 K
• do geometric “postmortem” & infer momentum
rate
25 october 2006
DNP 2006, Nashville - mike lisa
5
Microexplosions
Femtoexplosions
1018 K/sec
1035 K/s
• energy quickly deposited
s
0.1 J
1 J
• enter plasma phase
1017 J/m3
5 GeV/fm3 = 1036 J/m3
• expand hydrodynamically
•Tcool back to10original
phase 200 MeV = 1012 K
6 K
• do geometric “postmortem” & infer momentum
rate
25 october 2006
DNP 2006, Nashville - mike lisa
6
flow = ...
non-thermal p-space
non-exponential mT spectrum (“shoulder” versus mass)
number (even M-cumulant) anisotropy
global substructure of space-momentum correlations
most directly probed by measuring space-momentum correlations
25 october 2006
DNP 2006, Nashville - mike lisa
7
Femtoscopic information
xa
pa
pa
pb
pb
xa
xb
C (q) 
ab
P
Sab
( r )
P
xb
 d r S
3
( r )   (q, r )
2
= x a - x b  distribution
 (q, r ) = (a,b) relative wavefctn

know/assume relative wavefunction
 extract spatial distributions

25 october 2006
ab
P
OR
know/assume source distrib
 extract interaction (scat. length..)
DNP 2006, Nashville - mike lisa
8
R(√S
– simple
R(√SNN), b,
Npart, A,signal
B, mT,?y, , PID)
As with all soft sector observables,
not dramatic change with energy.
~10%
mass
Rout/Rside
What do we learn from detailed systematics?
s
pT
“”
Rischke, Gyulassy, NP A 608 (1996) 479
25 october 2006
DNP 2006, Nashville - mike lisa
9
R(√SNN, b, Npart, A, B, mT, y, , PID)
• Vary colliding system
• does physics change?
• requires dedicated program
• Vary kinematic variables
• space-time dynamics - flow
• requires large acceptance
mass
s
pT
• Vary particle type
• consistent picture?
• unique probe of dynamical structure
• requires good particle identification & acceptance
25 october 2006
DNP 2006, Nashville - mike lisa
10
Geometric substructure?
random (non-)system:
all observers measure the
“whole source”
25 october 2006
DNP 2006, Nashville - mike lisa
11
Flow-generated substructure
random (non-)system:
all observers measure the
“whole source”
Specific predictions of
bulk global collective flow:
• space-momentum (x-p) correlations
• faster (high pT) particles come from
•smaller source
•closer to “the edge”
25 october 2006
DNP 2006, Nashville - mike lisa
12
Consistent flow-dominated Blast-Wave picture
Spectra
v2
HBT
e.g. Sollfrank & Heinz ‘93
Retiere & MAL ‘03
25 october 2006
DNP 2006, Nashville - mike lisa
13
Nontrivial comparison to theory
cascade
hydro
•
•
•
•
Qualitatively, models reproduce scale and pT-dependence
Flow signal sensitive to physics input...
...AND apples::apples comparisons (c.f. Ko, Frodermann, Kisiel...)
Cascade models perform better
25 october 2006
DNP 2006, Nashville - mike lisa
14
Consistent flow-dominated Blast-Wave picture
Spectra
v2
HBT
e.g. Sollfrank & Heinz ‘93
Retiere & MAL ‘03
25 october 2006
DNP 2006, Nashville - mike lisa
15
Consistent flow-dominated Blast-Wave picture
+


-
K+ K- K0S p p











+







-




K+


K-
K

K0S
Rinv (fm)

6



p



p
• Huge PID systematics mapped
• Size vs mT consistent with global flow
4
2
25 october 2006
mT (GeV/c)
DNP 2006, Nashville - mike lisa
16
Consistent flow-dominated Blast-Wave picture
+


K
-
K+ K- K0S p p











+







-




K+


K-

K0S




p



p
• Huge PID systematics mapped
• Size vs mT consistent with global flow
• Position (shift) consistent !
25 october 2006
PRL 91 262301 (2003)DNP 2006, Nashville - mike lisa
17
Consistent flow-dominated Blast-Wave picture
+


K
-
K+ K- K0S p p











+







-




K+


K-

K0S




p



p
• Huge PID systematics mapped
• Size vs mT consistent with global flow
• Position (shift) consistent !
25 october 2006
DNP 2006, Nashville - mike lisa
18
Momentum-space consequences of flow
~
x  ~
xK(K ) 
lines: BlastWave fits
femtoscopy:
4
d
 x  x   x  S(x, K)
p



 d x  S( x, K)
4

4
d
 x  x   S( x, K)
 d x  S(x, K)
4Spectra

4
d
 x  x  S(x, K)
4
d
 x  S(x, K)
v2
PHENIX
STAR
PHOBOS
pT spectra:
dN
  dp  d 4 x  S( x, K )
pT dpT
p
v 2 ( p T , m) 
elliptic flow:
4
HBT
d

cos
2

d
x  S( x, K )
p
 p
4
d

d
 p  x  S(x, K)
BW: S(x,K) driven by , T
25 october 2006
DNP 2006, Nashville - mike lisa
19
“All” hadrons from S(x,K)? (Early FO?)
• , K, p: common
thermal freeze-out :
Au+Au
Au+Au at
at 200GeV
200GeV
T~90 MeV, <>~0.60 c
Chemical FO
FO temperature
temperature
Chemical
Chemical
FO
temperature
• , : Different
thermal FO behavior:
STAR PRELIMINARY
STAR PRELIMINARY
T~150MeV, <>~0.47c
→ Created earlier
in agreement with
a small sint
Magali Estienne, SQM04
But BlastWave is not “real” hydro
25 october 2006
DNP 2006, Nashville - mike lisa
20
The real deal and the mockup
Heinz&Kolb, PLB542 216 (2002)
F.O. hypersurfaces
(constant Tdec)
• hydro
• BW
But BlastWave is not “real” hydro
• hypersurface affects spectra (Kisiel et al)
• range of   heavy particles appear “hotter” (Retiere&MAL)
• heavy particles more at higher R  growing discrepancy w/ BW??
25 october 2006
DNP 2006, Nashville - mike lisa
21
The real deal and the common particles
Jeff Speltz, HotQuarks06
Central Data
• Best agreement for :
• Tdec= 100 MeV
• α = 0.02 fm-1
• α ≠ 0 : importance of initial
conditions
• τ0 = 0.6 fm/c
Tdec = 165 MeV
Tdec = 100 MeV
Model (plot) from P.F. Kolb and R. Rapp, Phys. Rev. C 67 (2003) 044903
25 october 2006
DNP 2006, Nashville - mike lisa
22
The real deal and the strange particles
Au+Au, s NN = 200 GeV
Au+Au, sNN = 62.4 GeV
Tdec = 164 MeV
Tdec = 100 MeV
Ω- spectra, central
P.F. Kolb and U. Heinz, nucl-th/0305084
•
Data best reproduced with
•
•
•
Tdec ≈ 100 MeV
Same as for π-, K-, p
Agreement holds for entire spectra
• Tdec ≈ 164 MeV (decoupling at hadronization):
not enough radial flow
25 october 2006
DNP 2006, Nashville - mike lisa
23
The real deal and the strange particles
Au+Au, sNN = 62.4 GeV
•
Data best reproduced with
•
•
•
Tdec ≈ 100 MeV
Same as for π-, K-, p
Agreement holds for entire spectra
• Tdec ≈ 164 MeV (decoupling at hadronization):
not enough radial flow
25 october 2006
DNP 2006, Nashville - mike lisa
BW interpretation of
common-source hydro
can vary by mass
due to artifacts
Occam says:
common global source
24
Where the excitement is : v2
• “All” particles - consistent with a
common bulk source
symmetry, thermal smearing
v2(pT,m) consistent with
anisotropic velocity field
(i.e. property of bulk)
25 october 2006
DNP 2006, Nashville - mike lisa
25
Where the excitement is : v2
• “All” particles - consistent with a
common bulk source
• (for the first time) - data meets ideal
hydro “limit”
• using realistic init. conditions
• early thermalization
• hope for access to EoS !
S. Voloshin
Kolb, Sollfrank, Heinz, PRC (2000)
dN/dy
25 october 2006
DNP 2006, Nashville - mike lisa
26
Where the excitement is : v2
• “All” particles - consistent with a
common bulk source
• (for the first time) - data meets ideal
hydro “limit”
• using realistic init. conditions
• early thermalization
• hope for access to EoS !
• PhaseKolb,
transition
in dense
state
Sollfrank, Heinz,
PRC (2000)
favored!
dN/dy
25 october 2006
S. Voloshin
Hydro: P. Huovinen, P. Kolb, U. Heinz
DNP 2006, Nashville - mike lisa
27
Where the excitement is : v2
thermalized
QGP EoS
initial cond.
• “All” particles - consistent with a
common bulk source
• (for the first time) - data meets ideal
hydro “limit”
• using realistic init. conditions
• early thermalization
• hope for access to EoS !
• Phase transition in dense state
favored!
25 october 2006
Hydro: P. Huovinen, P. Kolb, U. Heinz
DNP 2006, Nashville - mike lisa
28
But... EoS under control?
Huovinen, arXiv:nucl-th/0505036
• Unrealistic sharp 1st-order PT EoS
is required to fit data
• “Realistic” lattice parameterization
fits as poorly as hadronic EoS
• too much flow
• Detailed agreement with measured
v2(m,pT) an accident? (c.f. Hirano
& Gyulassy arXiv:nucl-th/0506049)
• Heinz, Ollitrault (private comm.):
should focus on PID (and pT)integrated v2
• ????
• Situation unclear but important
25 october 2006
DNP 2006, Nashville - mike lisa
29
... if not, then maybe should have too
much flow in model...
• c.f. Teaney PRC68 (2003)
• Ollitrault: “generic” hydro results
• v2/ driven only by EoS,
indep size
• v4/(v2)2 = 0.5
v4/(v2)2
But... thermalization assumption solid?
nucl-th/0508009
nucl-th/0506045
pT
v2/
S. Voloshin
this value
depends on c
25 october 2006
ct/RDNP 2006, Nashville - mike lisa
30
But... thermalization assumption solid?
... if not, then maybe should have too
much flow in model...
• c.f. Teaney PRC68 (2003)
• Ollitrault: “generic” hydro results
• v2/ driven only by EoS,
indep size
• v4/(v2)2 = 0.5
• But: do specific hydro codes satisfy
v4 requirement?
• No consensus on how “generic” is
this test of thermalization...
• Situation unclear but important
to develop tests of thermaliztion
indep of EoS, etc
25 october 2006
DNP 2006, Nashville - mike lisa
Kolb nucl-th/0306081
31
But... initial shape well-modeled?
Hirano et al PLB636 299 (2006)
• first calculations:
Glauber + ideal hydro
• CGC geometry might be more
realistic, (since fast thermalization
is often attributed to it)
• But...
• higher   way too much flow!
 need signif. early viscosity
• really need viscous 3D hydro
25 october 2006
DNP 2006, Nashville - mike lisa
32
But... initial shape well-modeled?
• first calculations:
Glauber + ideal hydro
• CGC geometry might be more
realistic (since fast thermalization
is often attributed to it)
• But...
• higher   way too much flow!
 need signif. early viscosity
• really need viscous 3D hydro
• recent: Lappi & Venugopalan:
• more correct CGC application
yields  ~ Glauber again
• Important & rapid developments
25 october 2006
DNP 2006, Nashville - mike lisa
Lappi&Venugopalan nucl-th/0609021
33
Collectivity in sQGP
• bulk, explosive flow-dominated system
• x-p substructure mapped in great detail
• femtoscopic quantities depend on physics in models
• quantitative comparison important and ongoing
• femtoscopy, spectra, v2
• bulk emitting system applies to “all” particles (prob. no early freezeout)
• BlastWave ≠hydro
• initial agreement b/t hydro & measured v2  “Perfect Liquid”
?
?
?
?
EoS
initial shape
thermalization
early viscosity
• Other open issues under investigation but not discussed
?
?
partonic (?) nature of collectivity
flow in p+p collisions ??
25 october 2006
DNP 2006, Nashville - mike lisa
34
The science is in the small print
Nature of EoS under
investigation ; agreement with
data may be accidental ;
viscous hydro under
development ; assumption
of thermalization in question
sensitive to modeling of
initial state,
presently under study
The detailed work now underway is what can probe & constrain sQGP properties
It is probably not press-release material...
...but, hey, you’ve already got your coffee mug
25 october 2006
DNP 2006, Nashville - mike lisa
35
25 october 2006
DNP 2006, Nashville - mike lisa
36
What drives the soft sector ?
H. Caines (STAR) QM05
NA57 (open)
STAR (filled)
LPSW nucl-ex/0505014
25 october 2006
NA57 (open)
STAR (filled)
S. Manly (PHOBOS) QM05
DNP 2006, Nashville - mike lisa
37
Paradigm shift
• many did not anticipate what turned out to be THE story of the bulk
• keep an open mind
• instead: “evolution rather than revolution” (the story of R.H.I.C.)
• “everything” scales only with multiplicity (indep A,B, s...)?!
• low-energy central collision ~ high-energy peripheral collision
• entropy is driving factor (more hydro-dominance)?
25 october 2006
DNP 2006, Nashville - mike lisa
38
Paradigm shift
• many did not anticipate what turned out to be THE story of the bulk
• keep an open mind
• instead: “evolution rather than revolution” (the story of R.H.I.C.)
• “everything” scales only with multiplicity (indep A,B, s...)?!
• low-energy central collision ~ high-energy peripheral collision
• entropy is driving factor (more hydro-dominance)?
• next logical step...
• again (like low s case) : is RHIC so different from pp ? bulk behaviour?
• again, keep an open mind
Au+Au 2002
p+p, 7 May 2006
25 october 2006
DNP 2006, Nashville - mike lisa
39
pp = “a small AA” ? ; Is geometry meaningful?
Collectivity is meaningless without geometry
Energy loss of energetic partons in quark-gluon plasma:
Possible extinction of high pT jets in hadron-hadron collisions
J.D. Bjorken, 1982
Au+Au 2002
p+p, 7 May 2006
25 october 2006
DNP 2006, Nashville - mike lisa
40
D. Kharzeev
Transverse Dynamics Workshop
March 2003
sure, but how would we know?
• theoretical prejudice
• experimental signatures
25 october 2006
DNP 2006, Nashville - mike lisa
41
Zbigniew Chajecki QM05
R Z(fm)
1. Heisenberg
uncertainty?
Z0 decay @ LEP
•2.e.g.
G. fragmentation?
Alexander
String
(Lund)
••3.“plausible”
ineffects?
z-direction
pResonance
maybe (??)
T dependence
•• unlikely
in transvrseprobably no
dependence
• mass
e.g. Wiedemann
& DELPHI
Heinz ‘97
[Andersson,
Moriond 2000]
• maybe,
but presumably
 different effect
significantly
femtoscopy in p+p @ RHIC
p+p and A+A measured in same
experiment
• unique opportunity to compare physics
• what causes pT-dependence in p+p?
• same cause as in A+A?
than for Au+Au
R (fm)
• under investigation

K
p 
STAR preliminary
hep-ph/0108194
25 october 2006
mT (GeV)
m, mT (GeV)
DNP 2006, Nashville - mike lisa
mT (GeV)
42
Zbigniew Chajecki QM05
3. Resonance effects?
4. Bulk system („hydro”)
in pp?
DELPHI
flow not expected in such
a small system as p+p
R (fm)
e.g. Shuryak: hep-ph/0405066

femtoscopy in p+p @ RHIC
p+p and A+A measured in same
experiment
• unique opportunity to compare physics
• what causes pT-dependence in p+p?
 in A+A?
• same cause as
1/(2mT)d2n/(dmTdy)
R Z(fm)
1. Heisenberg
uncertainty?
Z0 decay @ LEP
2. String fragmentation? (Lund)
K
p
mT-m (GeV)
 Csorgo et al.:
K Buda-Lund
treatment of p+p collision as
d+Au : Rlong doesn’t change
bulk
system
with centrality
p 
(w/ temperature gradients)
hep-ph/0406042
RSIDE
ROUT
RLONG
STAR preliminary
hep-ph/0108194
25 october 2006
mT (GeV)
m, mT (GeV)
DNP 2006, Nashville - mike lisa
mT (GeV)
mT (GeV)
43
Surprising („puzzling”) scaling
Ratio of (AuAu, CuCu, dAu) HBT
radii by pp
 All pT(mT) dependences of
HBT radii observed by STAR
scale with pp although it’s
expected that different origins
drive these dependences
HBT radii scale with pp
Scary coincidence
or something deeper?
pp, dAu, CuCu - STAR preliminary
25 october 2006
DNP 2006, Nashville - mike lisa
44
Other soft
“resembles data”
v2
Is the physics similar?
Is the data trying to tell us something?
PYTHIA 6.4 Minbias
(Single nondiffractive)
p+p @ 200 GeV
N.B.: Pythia mocks up the soft sector
Cannot, itself, (dis)prove flow/non-flow
What can we tell from the data?
25 october 2006
DNP 2006, Nashville - mike lisa
45
Is there a radial flow component ?
(blastwave fits to STAR data)
25 october 2006
DNP 2006, Nashville - mike lisa
46
There is an elliptic flow component
There is an interesting HBT component, see Mike Lisa’s talk
25 october 2006
DNP 2006, Nashville - mike lisa
47
p-p data
Not really going to
discuss – see Rene’s
talk
•Not just a base line!
•Interesting results in their
own right.
•Need to push for p-p at
the same energy.
•m
T
scaling - not absolute
Separate shape for
baryons and mesons
25 october 2006
STAR Preliminary
p-p 200 GeV
DNP 2006, Nashville - mike lisa
48
mT scaling and jets
Using PYTHIA split events into gluon and quark jet
Quark jet events show mass
dependence
Gluon jet events show
baryon/meson splitting
Gluon jet domination at RHIC? What happens at the LHC?
25 october 2006
DNP 2006, Nashville - mike lisa
49