Femtoscopy in heavy ion collisions:
Wherefore, Whence, & Whither?
Mike Lisa
Ohio State University
• Wherefore (=“why?”)
• motivation & (basic) formalism
• Whence (=“from where?”)
• systematics over 2 decades
• Whither (=“to where?”)
• or “wither”...?
http://www-rnc.lbl.gov/TBS
MAL, Pratt, Soltz, Wiedemann
Ann Rev Nucl Part Sci 55 (2005)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
1
Spacetime - The characteristic of H.I.C.
STAR, PRC66 (2002) 034904
STAR, PRL93 (2004) 252301
Ann.Rev.Nucl.Part.Sci. 46 (1996) 71
QuickTime™ and a
TIFF (L ZW) d eco mpres sor
are nee ded to s ee this picture.
• Non-trivial space-time - the hallmark of R.H.I.C.
• Initial state: dominates further dynamics
• Intermediate state: impt element in exciting signals
• Final state:
• Geometric structural scale is THE defining feature of QGP
• Temporal scale sensitive to deconfinement transition (?)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
2
Extraction of length scales
maximum-likelihood fit to
C (q) 
ab
P
 d r S
3
ab
P
( r )   (q, r )
2
usually used
(even for non-id)
Gaussian parameterization of a-b separation
 r X  r X 



i
i  j
j 
ab
SP ( r ) ~ exp  

2
4 i jR i, j


 i, j o,s,l

X i  x
a,i  x
b,i
;
i, j = out, side, long 
pa 


2
Cq    FQ inv   1 exp

q
q
R
  ipjb ij
 1 


 xa  ij

xa
• F(Qinv) = integratedxsquared
Coulomb wavefunction
b
xb
pa
for identical
pions
p
b
• “contamination” included via 
• NB: Gaussian source: not Gaussian CF
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
3
Reminder
• Two-particle interferometry: p-space separation  space-time separation
x1
p1

q
qside
p2
Rside
x2
qout
  
q  p2  p1
 1  
k  p 2  p1 
2
qlong
Rout
source sp(x) = homogeneity region [Sinyukov(95)]
 connections with “whole source” always model-dependent
Rside
Pratt-Bertsch (“out-side-long”)
decomposition designed to
help disentangle space & time
Rout
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
4
Disintegration timescale - INITIAL expectation
3D 1-fluid Hydrodynamics
Rischke & Gyulassy, NPA 608, 479 (1996)
with
transition
“”
“”
Long-standing favorite signature of QGP:
• increase in , ROUT/RSIDE due to deconfinement  confinement transition
• hoped-for “turn on” as QGP threshold is reached
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
5
Two decades of systematics
A.D. Chacon et al, Phys. Rev. C43 2670 (1991)
HBT
s ) Rep. Prog. Phys. 66 481 (2003)
G.(Alexander,
15
10
Heinz/Jacak
Wiedemann/Heinz
Csorgo
Tomasik/Wiedemann
Boal/Jennings/Gelbke
20
Lisa, Pratt, Soltz, Wiedemann
AGS/SPS/RHIC HBT papers (expt)
R = 1.2 (fm)•A1/3
“R = 5 fm”
5
‘85
‘90
‘95
‘00
‘05
• Pion HBT @ Bevalac: “largely confirming nuclear dimensions”
• Since 90’s: increasingly detailed understanding and study w/ high stats
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
6
Two decades of systematics
ˆ
HBT( s ;p T , y, b ,b,m
1 ,m2 ,Asys )
15
10
Heinz/Jacak
Wiedemann/Heinz
Csorgo
Tomasik/Wiedemann
Boal/Jennings/Gelbke
20
Lisa, Pratt, Soltz, Wiedemann
AGS/SPS/RHIC HBT papers (expt)
y
|b|
5
pT
‘85
‘90
‘95
‘00
‘05
• Pion HBT @ Bevalac: “largely confirming nuclear dimensions”
• Since 90’s: increasingly detailed understanding and study w/ high stats
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
7
Repeating most basic sanity check at relativistic energies...
Forget homogeneity regions or fancy stuff.
Do femtoscopic length scales increase when they “should?”
p-p correlations
* big bump  small source
 Also
• SPS [NA44(‘99),NA49(‘00)]
• RHIC [STAR(‘05)]
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
8
HBT( s ;p T , y, b , bˆ ,m1,m2 ,Asys )
Varying initial “source size”
Au+Au sNN =200 GeV
Fixed b : vary A (& B!)
• Generalize A1/3 Npart1/3
•not bad @ RHIC!
•connection w/ init. size?
Fixed A+B : vary b
Likely scaling variable: Npart
PHENIX, PRL 2004
b
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
9
HBT( s ;p T , y, b , bˆ ,m1,m2 ,Asys )
• Generalize A1/3 Npart1/3
•not bad @ RHIC!
•connection w/ init. size?
NB: not constant density
PHOBOS
• Heavy and light data from
AGS, SPS, RHIC
•~s-ordering in
“geometrical” Rlong, Rside
• Mult ~ K(s)*Npart
•source of residual s dep?
• ...Yes! common scaling
•final state drives radii, not
init. geometry
•(breaks down s < 5 GeV)
LPSW nucl-ex/0505014
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
10
Entropy determines “everything” at bulk level (soft sector)
?
c.f. Helen’s talk
H. Caines (STAR) QM05
H. Caines (STAR) QM05
We are not alone...
NA57 (open)
STAR
(filled)
Tounsi,
Mischke,
Redlich
NA57 (open)
STAR (filled)
NPA715 565 (2003)
S. Manly (PHOBOS) QM05
NB: scaling violated s < 4 GeV
(as with femtoscopy)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
11
Refinement: chemical effects
• different behaviour below/above AGS
• violates “universal” scaling
• baryon  meson dominance
Vf
• neglect time/dynamics: gross F.O.
geometry appears determined by
N
• chemistry
• “universal” mean free path ~ 1 fm (!?)
~ FO volume V f  (2 )
3/ 2
2
Rlong Rside
CERES, PRL 90 (2003) 022301
x-section: N   N i  i  N N   N  N   
i
m.f.p
 f Vf
f 

 ~ 1 fm
 N
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
12
Messages from systematics
• AB, |b|, Npart systematics
• sanity check on overall size dependence 
• final state multiplicity/chemistry determines rough geometry...
...and that geometry is ~2x initial size
collective/flow-like expansion?
 probe anisotropically!
c.f. Chajecki - lighter systems
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
13
HBT( s ;p T , y, b , bˆ ,m1,m 2 ,Asys )
Strongly-interacting 6Li released from an asymmetric trap
O’Hara, et al, Science 298 2179 (2002)
What can we learn?
?
in-planeextended
transverse FO shape
+ collective velocity
 evolution time estimate
check independent of RL(pT)
out-of-plane-extended
mike lisa - Femtoscopy in relativistic
Teaney,
heavy
Lauret,
ion &
collisions
Shuryak- nucl-th/0110037
Hot Quarks 17 May 2006, Sardinia, Italy
14
HBT( s ;p T , y, b , bˆ ,m1,m 2 ,Asys )
small RS
• observe the source from all angles
with respect to RP
• expect oscillations in HBT radii
big RS
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
15
HBT( s ;p T , y, b , bˆ ,m1,m 2 ,Asys )
• observe the source from all angles
with respect to RP
• expect oscillations in HBT radii
(including “new” cross-terms)
R2out-side<0
when pair=135º
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
16
HBT( s ;p T , y, b , bˆ ,m1,m 2 ,Asys )
Measured final source* shape
STAR, PRL93 012301 (2004)
R2out-side<0
when pair=135º
ever see that symmetry at ycm ?
*mike
model-dependent,
see Retiere
MAL
PRC70
044907
2004
lisa - Femtoscopy but
in relativistic
heavy&ion
collisions
- Hot
Quarks
17 May 2006, Sardinia, Italy
17
HBT( s ;p T , y, b , bˆ ,m1,m 2 ,Asys )
Measured final source* shape
STAR, PRL93 012301 (2004)
central
collisions
mid-central
collisions
peripheral
collisions
Expected evolution:
*mike
model-dependent,
see Retiere
MAL
PRC70
044907
2004
lisa - Femtoscopy but
in relativistic
heavy&ion
collisions
- Hot
Quarks
17 May 2006, Sardinia, Italy
18
Evolution of size and shape - “the rule of two”
R
 s;p ,y, b ,AB, ,m ,m 
T
bˆ
1
2
STAR PRL93 012301 (2004)


R 2y  R 2x
R 2y  R 2x
c.f. Chajecki - lighter systems
~ x2 size increase
~ 1/2 shape reduction
Initial size/shape estimated by Glauber calculation
Finalion
config
according
to Retiere
& MAL
2004
mike lisa - Femtoscopy in relativistic heavy
collisions
- Hot Quarks
17 May
2006, PRC70
Sardinia,044907
Italy
19
• non-trivial excitation function
• does it make sense? Is it
related to bulk dynamics?
 YES

“Anisotropic sanity check”
AGS: FO  init
RHIC: FO < init
(approximately same centrality)
sNN (GeV)
    v2   ???
is relation b/t final and 
near quantitatively sensible?
(in a toy model yes - for
discusison if asked)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
20
Messages from systematics
• AB, |b|, Npart systematics
• sanity check on overall size dependence 
• final state multiplicity/chemistry determines rough geometry...
• , |b|, s systematics
• sanity check on shape evolution 
• geometric evolution ~ consistent with collective bulk dynamics (flow)
look for dynamic signatures & substructure
• more than T versus mass
• more than spectral shapes
• more than v2
• ...
flow is defined by space-momentum correlations
only femtoscopy can probe substructure
of dynamic bulk behaviour
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
21
Geometric substructure?
random (non-)system:
all observers measure the
“whole source”
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
22
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”
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
23
Strong flow confirmed by all expts...
R
 s;p ,y, b ,AB, ,m ,m 
T
bˆ
1
2

what agreement!! (what agreement?)
LPSW(05)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
24
Flow-dominated
“Blast-wave” model
PRC70 044907 (2004)
Spectra
v2
HBT
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
25
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
Decreasing R(pT)
• usually attributed to collective flow
• flow integral to our understanding
of R.H.I.C.; taken for granted
• femtoscopy the only way to confirm
x-p correlations – impt check
Non-flow possibilities
• cooling, thermally (not collectively)
expanding source
• combo of x-t and t-p correlations
early times: small, hot source
late times: large, cool source
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
26
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
MAL et al, PRC49 2788 (1994)
Decreasing R(pT)
• usually attributed to collective flow
• flow integral to our understanding
of R.H.I.C.; taken for granted
• femtoscopy the only way to confirm
x-p correlations – impt check
Non-flow possibilities
• cooling, thermally (not collectively)
expanding source
• combo of x-t and t-p correlations
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
27
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
Decreasing R(pT)
• usually attributed to collective flow
• flow integral to our understanding
of R.H.I.C.; taken for granted
• femtoscopy the only way to confirm
x-p correlations – impt check
Non-flow possibilities
• cooling, thermally (not collectively)
expanding source
• combo of x-t and t-p correlations
• hot core surrounded by cool shell
• important ingredient of Buda-Lund
hydro picture
e.g. Csörgő & Lörstad
PRC54 1390 (1996)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
28
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
Each scenario generates
x-p correlations but…
Decreasing R(pT)
• usually attributed to collective flow
• flow integral to our understanding
of R.H.I.C.; taken for granted
• femtoscopy the only way to confirm
x-p correlations – impt check
x2-p correlation: yes
x-p correlation: yes
Non-flow possibilities
• cooling, thermally (not collectively)
expanding source
• combo of x-t and t-p correlations
• hot core surrounded by cool shell
• important ingredient of Buda-Lund
hydro picture
e.g. Csörgő & Lörstad
PRC54 1390 (1996)
t
x2-p correlation: yes
x-p correlation: no
x2-p correlation: yes
x-p correlation: no
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
29
Flow-dominated
“Blast-wave” model
PRC70 044907 (2004)
R (fm)
Spectra

v2
HBT
STAR PRL 91 262301 (2003)
K
mT (GeV/c)
space-momentum
substructure mapped in detail
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
30
RHIC femtoscopy with wide variety of particle species
R(√SNN, b, Npart, A, B, mT, y, , PID1, PID2)
+
-
K+
K-
p
p










+







-

-


K+



K-
-
-
K0S




p



p
K0S






 = prelim or final result available

mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
31
Trends, soft sector, and RHI history
Finally, we
• unlike
hard and
understand
it! “intermediate”
sectors, soft sector has “decades”
of systematics
A. Wetzler (2005)
Just one
event!
Then: p-dependent potentials, surface
effects, hard-cores, absoption...
M Gyulassy ‘95
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
32
model comparisons
• unlike hard and “intermediate”
sectors, soft sector has “decades”
of systematics
• single-point agreement a bit
unsatisfying...
• femtoscopic model comparisons:
mostly “HBT radii” in b=0 collisions
• RHIC models only expected to
work at highest energies...
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
33
Comparison to “perfect” hydro calculations
LPSW(05)
• model sensitivity (not just R=5)
•Rout too big (too long emission time?)
• Rlong too big (too long evolution time?)
• Rside too
small
(?) - Hot Quarks 17 May 2006, Sardinia, Italy
mike lisa - Femtoscopy in relativistic
heavy
ion collisions
34
Comparison to Boltzmann/cascade models
better! (better than “perfect”...?)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
35
What’s the difference?
freeeze-out........ EoS............viscosity
hydro
“HBT radii” from variances
R 2o  x˜ 2  2 T x˜  ˜t   T2 ˜t 2
RS2  y˜ 2
; R 2L  z˜ 2
cascade
fit calculated* 3D C(q)
to Gaussian functional form:
C(q)  1   e
q 2o R 2o q 2s R 2s q 2l R 2l
*later: how it is calculated
theionsame
IF- source
mike lisa - Femtoscopy inshould
relativisticbe
heavy
collisions
Hot Quarksis17Gaussian
May 2006, Sardinia, Italy
36
Non-Gaussian Effects and Model Comparisons - Hydro/BW
Frodermann, Heinz, MAL PRC63 (2006)
C2
C2
Hydrodynamics - CE EOS
Hydrodynamics - NCE EOS
Frodermann, Heinz, MAL PRC63 (2006)
Frodermann, Heinz, MAL PRC63 (2006)

Blast Wave
C2


Depending on model (& parameters, like EoS),
non-Gauss effects may qbe
important, (also, Hirano,
Ko/Li, Rischke)
qs (GeV/c)
s (GeV/c)
• BW - no big effect
• “perfect” hydro - pushes results into “right” direction. NCE EoS close
RO
KT (GeV/c)
KT (GeV/c)
KRTS(GeV/c)
KT (GeV/c)
RL
 KT (GeV/c)
KT (GeV/c)
qs (GeV/c)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
37
Wherefore & Whence
R(√SNN, b, Npart, A, B, mT, y, , PID1, PID2)
• size & shape; timescale estimate
• space-momentum substructure of a flowing system;
dynamics and evolution of
• radial flow (size and shift)
• elliptic flow (shape and timescale)
• directed flow (shape and tilt)
[did not show due to time]
• hadronic particle potentials / phase shifts
• Femtoscopy:
•
•
•
•
well-calibrated, well-established tool
the one most directly connected to space-time - THE defining feature of R.H.I.C.
huge set of systematics of consistent measurements
sensitive to physics in models
• with care: the femtoscope is a precision tool to apply to new systems
LHC, p+p, etc
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
38
Whither?
• non-id correlations for b≠0
[Retiere & Lisa PRCPRC70 044907 (2004)]
• invert the problem : low-energy phaseshifts from exotic pairs (e.g. -)
[talk of H. Gos] & [P. Chaloupta QM05]
• space-time substructure in p+p ?? - “direct comparison] [talk of Z. Chajecki]
[Chajecki et al, WW05]
• imaging - beyond sizes and shifts [Brown, Danielewicz, Pratt, & others]
• first-order azimuthally-sensitive femtoscopy - spacetime aspects of v1
[Lisa et al, PLB489 287; PLB496 1]
• relative jets, spin.... (?)
• continue/expand rich program @ ALICE/LHC
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
39
THE
END
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
40
Strong flow confirmed by all expts...
R
 s;p ,y, b ,AB, ,m ,m 
T
bˆ
1
2
Ri
R i mT    i
mT


Central (~10%) AuAu (PbPb) collisions at y~0
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
41
A simple estimate – 0 from init and final
• BW → X, Y @ F.O. (X > Y)
• hydro: flow velocity grows ~ t
  X ,Y ( t )   X ,Y (F.O.) 
t
0
• From RL(mT): 0 ~ 9 fm/c
consistent picture
• Longer or shorter evolution times
X inconsistent
P. Kolb, nucl-th/0306081
toy estimate: 0 ~ 0(BW)~ 9 fm/c
• too short to account for expansion??
• Need a real model comparison
→ asHBT workable “evolutionary
clock” constraint for models
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
MAL ISMD03
42
Motivation
Formalism
Experiment
Trends
Models
1D projections: a limited view
STAR PRC71 044906 (2005)
• Usually, quality of data and fit
shown in 1D projections
• Narrow integration best
out
“Gaussian fit”
(remember: not
Gaussian CF)
• limited view of data
• see talks of Adam, Scott,
Sandra
• tomorrow: a better way
side
long
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
43
Motivation
Formalism
Experiment
Trends
Models
The perennial non-Gaussianness
• Source has never been fully Gaussian.
c.f. J. Sullivan @ SPS
• periodically re-discovered, with little
change; information condensation
needed to observe systematic data
trends
• non-Gaussianness @ RHIC reported in
first and subsequent HBT measurements
• imaging is probably best solution (but
even then...)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
44
Motivation
Formalism
Experiment
Trends
Models
The perennial non-Gaussianness
CF is “mostly” Gaussian
STAR tried “Edgeworth”
functional expansion
(Csorgo 2000)
STAR PRC71 044906 (2005)
Rl (fm)
• 20% effect in Rlong! systematic error...?
• appears fit captures dominant length scale
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
RO/RS
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and
QuickTime™
and aa
TIFF (LZW)
(LZW) decompressor
decompressor
TIFF
are needed to see this picture.
are needed to see this picture.
RS (fm)
RO (fm)
among few quantitative estimates
of non-Gaussian shape
45
Another implication of strong flow: ~ mT scaling
R
 s;p ,y, b ,AB, ,m ,m 
T
bˆ
1
2

mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
46
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )

R 2y  R 2x
R 2y  R 2x
AGS: FO  init
• transverse shape:
• non-trivial excitation function
• increased flow*time  rounder
FO geometry @ RHIC
• insufficient [flow]x[time] to
become in-plane
RHIC: FO < init
(approximately same centrality)
using four of the six “radii”

ri X i  rj X j 



ab
SP ( r ) ~ exp  

2
4 i jR i, j


 i, j o,s,l

X i  x
a,i  x
b,i
;
sNN (GeV)
i, j = out, side, long 
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
47
using ALL of the six “radii”

ri X i  rj X j 



S ( r ) ~ exp  

2
4 i jR i, j


 i, j o,s,l

ab
P
X i  x
a,i  x
b,i
;
i, j = out, side, long 
Au+Au sNN = 2.3 GeV; b5 fm

E895, PLB496 1 (2000)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
48
 (o)
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
AGS
• transverse shape:
• non-trivial excitation function
• increased flow*time  rounder
FO geometry @ RHIC
• insufficient [flow]x[time] to
become in-plane
• Spatial orientation:
• another handle on flow & time
• HUGE tilts @ AGS!!
• RHIC?
• QGP-induced orientation?
STAR: soon
?
?
sNN (GeV)
y
x
s
z
(Beam)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
49
v1 predictions (QGP invoked)
x-p transverse-longitudinal coupling may be affected in early (v1) stage
J. Brachmann et al., Phys. Rev. C. 61 024909 (2000)
L.P. Csernai, D. Rohrich:
Phys. Lett. B 458 (1999)
454
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
50
 ( o)
HBT( s ; p T , y, b , bˆ ,m1,m 2 ,Asys )
AGS
• transverse shape:
• non-trivial excitation function
• increased flow*time  rounder
FO geometry @ RHIC
• insufficient [flow]x[time] to
become in-plane
• Spatial orientation:
• another handle on flow & time
• HUGE tilts @ AGS!!
• RHIC?
• QGP-induced orientation?
• requires true 3D dynamical
model (explicitly non-B.I.)
STAR: soon ?
?
?
sNN (GeV)
y
x
s
z
(Beam)
mike lisa - Femtoscopy in relativistic heavy ion collisions - Hot Quarks 17 May 2006, Sardinia, Italy
51