RHIC HBT in a larger context

Z. Ch. - WPCF 2008, Krakow, Poland, Sep. 11-14 2008 1

RHIC HBT RHIC HBT in a larger contextin a larger context

Zbigniew Chajęcki, OSU

for the Experiment


OutlineOutline

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?


Heavy ions at RHICHeavy ions at RHIC

Multidimensional analysis at RHIC

R(√SNN, mT, b, Npart, A, B, PID)

... but is there a scaling variable?


Multiplicity scaling of HBT radii at Multiplicity scaling of HBT radii at RHICRHIC

Radii scale with multiplicity

Lisa, Pratt, Soltz, Wiedemann, Ann.Rev.Nucl.Part.Sci. 55 (2005) 357-402


Flow is the most important bulk feature at RHIC mT-dependence of femtoscopy probes flow

the most directly quantitative agreement w/p-only observables

[email protected]% centrality

mmTT dependence of pion HBT dependence of pion HBT radiiradii


Femtoscopy - direct evidence of Femtoscopy - direct evidence of flowflow

Spectra

v2

HBT

Flow-dominated “Blast-wave”toy models capture main characteristicse.g. PRC70 044907 (2004)

KR

(fm

)

mT (GeV/c)

STAR PRL 91 262301 (2003)

space-momentum substructure mapped in detail

6


Id-pion correlations in p+pId-pion correlations in p+p

STAR preliminary

mT [GeV/c2] mT [GeV/c2]

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?

€

mT = kT2 + mπ

2


Femtoscopy in pp vs heavy Femtoscopy in pp vs heavy ionsions

pp, dAu, CuCu - STAR preliminary

Ratio of (AuAu, CuCu, dAu) HBT radii by ppHBT radii scale with pp

Scary coincidence or something deeper?


Z.Ch., Gutierrez, Lisa, Lopez-Noriega, [nucl-ex/0505009]

Pratt, Danielewicz [nucl-th/0501003]

Non-femto correlations / SH Non-femto correlations / SH representationrepresentation

d+Au: peripheral collisions

STAR preliminary

∑→→ ΔΔ

=binsall

iiiiimlml QCYQA

.

,cos

, ),cos|,(|),(4

|)(| φθφθπ

φθ

STAR preliminary


Decomposition of CF onto Spherical Decomposition of CF onto Spherical HarmonicsHarmonics

Au+Au: central collisions

C(Qout)

C(Qside)

C(Qlong)

∑→→ ΔΔ

=binsall

iiiiimlml QCYQA

.

,cos

, ),cos|,(|),(4

|)(| φθφθπ

φθ

Z.Ch., Gutierrez, Lisa, Lopez-Noriega, [nucl-ex/0505009]

Pratt, Danielewicz [nucl-th/0501003]

Qx<0.03 GeV/c


Non-femtoscopic correlations in Non-femtoscopic correlations in STARSTAR

Baseline problem is increasing

with decreasing multiplicity

STAR preliminary

N-dep. of non-femtoscopic correlations in p+p

STAR preliminary


EMCICs in other experimentsEMCICs in other experiments

CLEO PRD32 (1985) 2294

NA22, Z. Phys. C71 (1996) 405

Qx<0.04 GeV/cOPAL, Eur. Phys. J. C52 (2007) 787-803

Qx<0.2 GeV/cNA23, Z. Phys. C43 (1989) 341

E766, PRD 49 (1994) 4373M

ultip

licity

incr

ease

s


€

C(qo,qs,ql ) = C femto(qo,qs,ql ) ⋅F(qo,qs,ql )

€

F(qo,qs,ql ) = 1+ δo qo + δs qs + δl ql

€

F(qo,qs,ql ) = 1+ δoqo + δsqs + δlql

• MC simulations

• ‘ad-hoc’ parameterizations

• OPAL, NA22, …

Common approaches to „remove” Common approaches to „remove” non-femtoscopic correlationsnon-femtoscopic correlations

• An alternative explanation:Energy and Momentum Conservation Induced Correlations, Z.Ch. and Mike Lisa [ArXiv:0803.022, sub. to PRC]

• “zeta-beta” fit by STAR [parameterization of non-femtoscopic correlations in Alm’s]

€

C( p1, p2 ) ≅ C femto p1, p2( ) 1−1

N2

r p T ,1 ⋅

r p T,2

pT2

+pz,1 ⋅ pz,2

pz2

+E1 − E( ) ⋅ E2 − E( )

E 2 − E2

⎛

⎝

⎜ ⎜ ⎜

⎞

⎠

⎟ ⎟ ⎟

⎡

⎣

⎢ ⎢ ⎢

⎤

⎦

⎥ ⎥ ⎥

|Q| |Q|

|Q|


How do EMCICs look?How do EMCICs look?

mike lisa - Nuclear Physics & RIKEN Theory Seminar 8 Aug 2008 14

€

C(p1,p2) ≅1−1

N2

r p T,1 ⋅

r p T,2

pT2

+pz,1 ⋅pz,2

pz2

+E1 − E( ) ⋅ E 2 − E( )

E 2 − E2

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

€

Detailed shape depends on:

N, E , E 2 , pT2 , pZ

2

and kinematic cuts

GenBod calculations


EMCIC fit to STAR p+p dataEMCIC fit to STAR p+p data

15

λ = 0.38 ± 0.01 Ro = 0.65 ± 0.01 fmRs = 0.85 ± 0.02 fmRl = 1.42 ± 0.02 fm

λ = 0.38 ± 0.01 Ro = 0.65 ± 0.01 fmRs = 0.85 ± 0.02 fmRl = 1.42 ± 0.02 fm

15

λ = 0.69 ± 0.01 Ro = 0.98 ± 0.03 fmRs = 0.94 ± 0.02 fmRl = 1.46 ± 0.03 fm

λ = 0.69 ± 0.01 Ro = 0.98 ± 0.03 fmRs = 0.94 ± 0.02 fmRl = 1.46 ± 0.03 fm

N = 15<E> = 0.39 GeV<E2> = 0.19 GeV2

<pT2> = 0.5 GeV2

<pz2> = 0.25 GeV2

N = 15<E> = 0.39 GeV<E2> = 0.19 GeV2

<pT2> = 0.5 GeV2

<pz2> = 0.25 GeV2

STAR preliminary

€

C femto(qo,qs,ql ) = 1− λ( ) + λ ⋅Kc (qinv ) 1+ e−qo2 Ro

2 −qs2 Rs

2 −ql2 Rl

2

[ ]

standard fit


EMCIC fit to STAR p+p dataEMCIC fit to STAR p+p data

16

λ = 0.69 ± 0.01 Ro = 0.96 ± 0.04 fmRs = 0.98 ± 0.03 fmRl = 1.26 ± 0.02 fm

λ = 0.69 ± 0.01 Ro = 0.96 ± 0.04 fmRs = 0.98 ± 0.03 fmRl = 1.26 ± 0.02 fm

N = 10.3<E> = 0.61 GeV<E2> = 0.43 GeV2

<pT2> = 0.2 GeV2

<pz2> = 0.4 GeV2

N = 10.3<E> = 0.61 GeV<E2> = 0.43 GeV2

<pT2> = 0.2 GeV2

<pz2> = 0.4 GeV2

λ = 0.38 ± 0.01 Ro = 0.65 ± 0.01 fmRs = 0.85 ± 0.02 fmRl = 1.42 ± 0.02 fm

λ = 0.38 ± 0.01 Ro = 0.65 ± 0.01 fmRs = 0.85 ± 0.02 fmRl = 1.42 ± 0.02 fm

STAR preliminary


Various fits to STAR p+p dataVarious fits to STAR p+p data

STAR preliminary

STAR preliminary


mmTT scaling of HBT radii scaling of HBT radii

Various fits give different radii but mT scaling of HBT radii is preserved in all fits

p+p HBT looks like flow!

STAR preliminary


Multiplicity dependence in p+pMultiplicity dependence in p+p

200 GeV

Rin

v [

fm]

STAR preliminary


p+p vs heavy ions - R(N,mp+p vs heavy ions - R(N,mTT))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 …


Femtoscopy in small systemsFemtoscopy in small systemsSystem √s [GeV] Facility Experiment

p-p 7.2 AGS E766

17 SPS NA49 -prelim

26 SPS NA23

27.4 SPS NA27

31-62 ISR AFS

44,62 ISR ABCDHW

200 SPS NA05

200 RHIC STAR

~1.9 LEAR CPLEAR

p-p 53 ISR AFS

200 SPS NA05

200-900 SPS UA1

1800 Tevatron E735

- 126 ISR AFS

h-p 21.7 SPS EHS/NA22

System √s[GeV] Facility Experiment

e+e- 3 SLAC Mark-II

10 CESR CLEO

29 SLAC TPC

34 TASSO

58 TRISTAN AMY

91 LEP OPAL

91 LEP L3

91 LEP DELPHI

91 LEP ALEPH

e-p HERA ZEUS

e-A HERA HERMES

R ≈ 0.5 - 1.5 fm


My first impression My first impression

€

C = 1+ λ exp −Rinv2 Qinv

2( )

€

C = 1+ λ exp −RG2 QG

2 + Q02τ 2

( )

€

C = 1+ λ2J1 qT RB( )

qT RB

⎡

⎣ ⎢ ⎢

⎤

⎦ ⎥ ⎥

2

1+ qocτ( )−1

€


2( )[ ] 1+ δ ⋅Qinv( )

€


2( )[ ] 1+ δ ⋅Qinv

2( )

€


2( )

€

C = 1+ λ2J1 qT RB( )

qT RB

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

2 ⎡

⎣

⎢ ⎢ ⎢

⎤

⎦

⎥ ⎥ ⎥1+ δB ⋅qT( )

€

C = 1+ λ exp −Re Qinv( )

€

C = 1+ λ1 exp −R12Q2

( ) + λ2 exp −R22Q2

( )

€


2( )[ ] 1+ ε ⋅Qinv + δ ⋅Qinv

2( )

€

C = 1+ λ2J1 qT RB( )

qT RB

⎡

⎣ ⎢ ⎢

⎤

⎦ ⎥ ⎥

2

1+ qocτ( )2 ⎛

⎝ ⎜

⎞ ⎠ ⎟−1

€


2( )[ ] 1+ δ ⋅Qinv

2( )

−1

€

C = 1+ λ2J1 qT RB( )

qT RB

⎡

⎣ ⎢ ⎢

⎤

⎦ ⎥ ⎥

2

1+ qLcτ( )−1

Can we do a direct comparison between experiments?


Parameterizations of 1D CF used in Parameterizations of 1D CF used in comparision b/w experimentscomparision b/w experiments

€


2( )

€


2 + Q02τ 2

( )

€

C = 1+ λ2J1 qT RB( )

qT RB

⎡

⎣ ⎢ ⎢

⎤

⎦ ⎥ ⎥

2

1+ qocτ( )−1

€

⎫

⎬

⎪ ⎪ ⎪

⎭

⎪ ⎪ ⎪

RB≈2·RG


• 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:0807.3569Same 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

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SummarySummary


www.femtoscopy.orgwww.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

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RHIC HBT in a larger context

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