Transcript Indentical Particle Correlations with STAR

RHIC HBT
in a larger context
Zbigniew Chajęcki, OSU
for the
Experiment
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
1
Outline
 HBT in Heavy-Ion Collisions at RHIC
 Multiplicity as universal scaling
 R(mT) - direct probe of flow scenario
 Femtoscopy in p+p [reminder]
 mT scaling of HBT radii (AA/pp) [reminder]
 Energy and Momentum Conservation Induced Correlations
in p+p
 STAR results from p+p (all fits)
 world systematics : Rinv(N,mT), Ro,s,l(mT)
 How different is pp from AA at the end?
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
2
Heavy ions at RHIC
Multidimensional analysis at RHIC
R(√SNN, mT, b, Npart, A, B, PID)
... but is there a scaling variable?
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
3
Multiplicity scaling of HBT radii at RHIC
Radii scale
with
multiplicity
Lisa, Pratt, Soltz,
Wiedemann,
Ann.Rev.Nucl.Part.Sci.
55 (2005) 357-402
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
4
mT dependence of pion HBT radii
[email protected]
0-10% centrality
 Flow is the most
important
bulk feature at RHIC
 mT-dependence
of femtoscopy probes flow
the most directly
 quantitative agreement
w/p-only observables
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
5
Femtoscopy - direct evidence of flow
R (fm)
Spectra
v2

K
HBTSTAR PRL 91 262301 (2003)
Flow-dominated “Blast-wave”
toy models capture main characteristics
e.g. PRC70 044907 (2004)
mT (GeV/c)
space-momentum substructure
mapped in detail
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
66
Id-pion correlations in p+p
 p+p and A+A measured
in thesame experiment
 great opportunity
to compare physics
 what causes
pT-dependence in p+p?
 same cause as in A+A?
STAR preliminary
mT [GeV/c2]
mT [GeV/c2]
mT  kT2  m2
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
7
Femtoscopy in pp vs heavy ions
HBT radii scale with pp
Ratio of (AuAu, CuCu, dAu) HBT
radii by pp
Scary coincidence
or something deeper?
pp, dAu, CuCu - STAR preliminary
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
8
Non-femto correlations / SH representation
d+Au:
peripheral collisions

Al ,m (| Q |) 
STAR preliminary
STAR preliminary
 cos 
4
all .bins

i

Yl ,m ( i , i )C (| Q |, cos i , i )
Z.Ch., Gutierrez, Lisa,
Lopez-Noriega, [nucl-ex/0505009]
Pratt, Danielewicz [nucl-th/0501003]
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
9
Decomposition of CF onto Spherical Harmonics
Au+Au:
central collisions
C(Qout)
C(Qside)

Al ,m (| Q |) 
 cos 
4
all .bins


Yl ,m ( i , i )C (| Q |, cos i , i )
i
Z.Ch., Gutierrez, Lisa,
Lopez-Noriega, [nucl-ex/0505009]
C(Qlong)
Pratt, Danielewicz [nucl-th/0501003]
Qx<0.03 GeV/c
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
10
Non-femtoscopic correlations in STAR
N-dep. of non-femtoscopic correlations in p+p
Baseline problem is increasing
with decreasing multiplicity
STAR preliminary
STAR preliminary
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
11
Multiplicity increases
EMCICs in other experiments
Qx<0.2 GeV/c
E766, PRD 49 (1994) 4373
NA23, Z. Phys. C43 (1989) 341
Qx<0.04 GeV/c
OPAL, Eur. Phys. J. C52 (2007) 787-803
NA22, Z. Phys. C71 (1996) 405
CLEO PRD32 (1985) 2294
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
12
Common approaches to „remove”
non-femtoscopic correlations
• MC simulations
• ‘ad-hoc’ parameterizations
• OPAL, NA22, …
C(qo,qs,ql )  C femto(qo,qs,ql )  F(qo,qs,ql )
F(qo,qs,ql )  1 ooqqoosqs sqs 
lql ql

b
|Q|
|Q|
z
• “zeta-beta” fit by STAR
[parameterization of non-femtoscopic correlations in Alm’s]


• An alternative explanation:
Energy and Momentum Conservation Induced Correlations,
Z.Ch. and Mike Lisa [ArXiv:0803.022, sub. to PRC]



E

E

E

E
p p
1
2
 1  p  p

C( p1, p2 )  C femto p1, p2 1 2 T,1 2 T,2  z,1 2 z,2 
2


2
N 

p
p
E

E
T
z








Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008

|Q|

13
How do EMCICs look?
GenBod
calculations
Detailed shape depends on:
N, E , E 2 , pT2 , p2Z
and kinematic cuts


1  pT,1  pT,2 pz,1  pz,2 E1  E  E 2  E 
C(p1,p2 ) 1 2


2
2
2


NZ.Ch. - WPCF
pT 2008, Krakow,
pz Poland, Sep. 11-14
E 2 2008
 E

14
EMCIC fit to STAR p+p data
λ = 0.38 ± 0.01
Ro = 0.65 ± 0.01 fm
Rs = 0.85 ± 0.02 fm
Rl = 1.42 ± 0.02 fm
λ = 0.69 ± 0.01
Ro = 0.98 ± 0.03 fm
Rs = 0.94 ± 0.02 fm
Rl = 1.46 ± 0.03 fm
STAR preliminary
standard fit
qo2 Ro2 q s2 R s2 ql2 Rl2
femto
C
(qo,qs,ql )  1     K c (qinv ) 1 e
 


Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
N = 15
<E> = 0.39 GeV
<E2> = 0.19 GeV2
<pT2> = 0.5 GeV2
<pz2> = 0.25 GeV2
15
15
EMCIC fit to STAR p+p data
λ = 0.38 ± 0.01
Ro = 0.65 ± 0.01 fm
Rs = 0.85 ± 0.02 fm
Rl = 1.42 ± 0.02 fm
λ = 0.69 ± 0.01
Ro = 0.96 ± 0.04 fm
Rs = 0.98 ± 0.03 fm
Rl = 1.26 ± 0.02 fm
STAR preliminary
N = 10.3
<E> = 0.61 GeV
<E2> = 0.43 GeV2
<pT2> = 0.2 GeV2
<pz2> = 0.4 GeV2
16
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
16
Various fits to STAR p+p data
STAR preliminary
STAR preliminary
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
17
mT scaling of HBT radii
STAR preliminary
Various fits give
different radii but mT
scaling of HBT radii
is preserved in all fits
p+p HBT
looks like flow!
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
18
Multiplicity dependence in p+p
STAR preliminary
Rinv [fm]
200 GeV
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
19
p+p vs heavy ions - R(N,mT)
STAR preliminary
Similar mT and multiplicity dependence of
HBT radii in p+p and heavy ions in STAR
Is STAR p+p unique? Let’s look at world’s
results on HBT in elementary particle
collisions …
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
20
Femtoscopy in small systems
System
√s [GeV]
Facility
Experiment System
√s[GeV]
Facility
Experiment
p-p
7.2
AGS
E766
3
SLAC
Mark-II
17
SPS
NA49 -prelim
10
CESR
CLEO
26
SPS
NA23
29
SLAC
TPC
27.4
SPS
NA27
34
31-62
ISR
AFS
58
TRISTAN
AMY
44,62
ISR
ABCDHW
91
LEP
OPAL
200
SPS
NA05
200
RHIC
STAR
91
LEP
L3
~1.9
LEAR
CPLEAR
91
LEP
DELPHI
53
ISR
AFS
91
LEP
ALEPH
200
SPS
NA05
e-p
HERA
ZEUS
200-900
SPS
UA1
e-A
HERA
HERMES
1800
Tevatron
E735
-
126
ISR
AFS
h-p
21.7
SPS
EHS/NA22
p-p
e+e-
TASSO
R ≈ 0.5 - 1.5 fm
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
21

My first impression

2
2
C  1  exp Rinv
Qinv

2
1   Qinv    Qinv

C  1  exp R Q


2
inv
2
inv




2
2
C  1  exp Rinv
Qinv


C  1  exp Re Qinv


C  1 1 exp R12Q2  2 exp R22Q2


2J q R
1 T B
C  1 

 qT RB



 1 q c




2
1
L

2J q R 

1 T B


1 qoc
C  1 

q
R

 T B 

2 2
2
G G
0
2
 

C  1  exp R Q  Q 
2
1   
Qinv


2 2
C

1

exp
R
Can we do a direct
comparison
G QG
2

2

1


2


2Jbetween
experiments?
q
R
1
1 T B
 1 qoc
C  1 
 qT RB 
C  1  expR Q 1   Q 


  
2 



2J q R
1 T B


2
2
C  1  expRinv
Qinv
1   Qinv  C 1  qT RB
 2008

Sep. 11-14
Z. Ch. - WPCF 2008, Krakow, Poland,
2
inv
2
inv
 1 
 
 

2
inv
B
 qT
1

22
Parameterizations of 1D CF used in
comparision b/w experiments

2
2
C  1  exp Rinv
Qinv


C  1  exp R Q  Q 

2
G
2J q R
1 T B

C  1 
q
R

T
B

2
G

2 2
0


 1 qoc


2






1




RB≈2·RG

Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
23
Summary
•
•
•
•
Femtoscopy similar in p+p as in Au+Au @ STAR
“World results” show both pT and N dependence!
EMCICs seen in small systems
differences observed in pT spectra consistent with
EMCIC “distortion” of unchanging parent distribution
(soft sector) - talk by Mike Lisa & arXiv:0807.3569
Same physics in p+p as in Au+Au and the only difference
due to phase-space effects?
possibilities:
1.spectra and HBT are insensitive to underlying physics (flow
etc)
2.they are sensitive & the very different physics of A+A and p+p
look coincidentally identical
3.they are sensitive, and driving physics is the same
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
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www.femtoscopy.org
Database of talks/proceedings on particle
correlations and related topics
Femtoscopy.org in numbers
• Meetings : 24 records
• Speakers : 117 records
• Talks
: 248 records
• Files
: 295 records
Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008
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