RHIC HBT in a larger context

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RHIC HBT in a larger context

• Zbigniew Chajecki, OSUfor the
  Experiment

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Outline

• HBT in Heavy-Ion Collisions at RHIC
• Multiplicity as universal scaling
• R(mT) - direct probe of flow scenario
• Femtoscopy in pp reminder
• mT scaling of HBT radii (AA/pp) reminder
• Energy and Momentum Conservation Induced
  Correlations in pp
• STAR results from pp (all fits)
• world systematics Rinv(N,mT), Ro,s,l(mT)
• How different is pp from AA at the end?

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Heavy ions at RHIC
Multidimensional analysis at RHICR(vSNN, mT, b,
Npart, A, B, PID) ... but is there a scaling
variable?
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Multiplicity scaling of HBT radii at RHIC
Radii scale with multiplicity
Lisa, Pratt, Soltz, Wiedemann,
Ann.Rev.Nucl.Part.Sci. 55 (2005) 357-402
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mT dependence of pion HBT radii
AuAu_at_19.6GeV 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

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Femtoscopy - direct evidence of flow
?
K
Flow-dominated Blast-wave toy models capture
main characteristics e.g. PRC70 044907 (2004)
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Id-pion correlations in pp

• pp and AA measured in thesame experiment
• great opportunity to compare physics
• what causes pT-dependence in pp?
• same cause as in AA?

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Femtoscopy in pp vs heavy ions
Ratio of (AuAu, CuCu, dAu) HBT radii by pp
HBT radii scale with pp Scary coincidence or
something deeper?
pp, dAu, CuCu - STAR preliminary
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Non-femto correlations / SH representation
STAR preliminary
Z.Ch., Gutierrez, Lisa, Lopez-Noriega,
nucl-ex/0505009 Pratt, Danielewicz
nucl-th/0501003
STAR preliminary
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Decomposition of CF onto Spherical Harmonics
Qxlt0.03 GeV/c
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Non-femtoscopic correlations in STAR
Baseline problem is increasing with decreasing
multiplicity
STAR preliminary
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EMCICs in other experiments
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Common approaches to remove non-femtoscopic
correlations

• MC simulations
• ad-hoc parameterizations
• OPAL, NA22,

• zeta-beta fit by STAR parameterization of
  non-femtoscopic correlations in Alms

• An alternative explanationEnergy and Momentum
  Conservation Induced Correlations, Z.Ch. and
  Mike Lisa ArXiv0803.022, sub. to PRC

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How do EMCICs look?
GenBod calculations
mike lisa - Nuclear Physics RIKEN Theory
Seminar 8 Aug 2008
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EMCIC fit to STAR pp data
? 0.38 0.01 Ro 0.65 0.01 fm Rs 0.85
0.02 fm Rl 1.42 0.02 fm
? 0.69 0.01 Ro 0.98 0.03 fm Rs 0.94
0.02 fm Rl 1.46 0.03 fm
N 15 ltEgt 0.39 GeV ltE2gt 0.19 GeV2 ltpT2gt
0.5 GeV2 ltpz2gt 0.25 GeV2
STAR preliminary
standard fit
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EMCIC fit to STAR pp data
? 0.38 0.01 Ro 0.65 0.01 fm Rs 0.85
0.02 fm Rl 1.42 0.02 fm
? 0.69 0.01 Ro 0.96 0.04 fm Rs 0.98
0.03 fm Rl 1.26 0.02 fm
N 10.3 ltEgt 0.61 GeV ltE2gt 0.43 GeV2 ltpT2gt
0.2 GeV2 ltpz2gt 0.4 GeV2
STAR preliminary
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Various fits to STAR pp data
STAR preliminary
STAR preliminary
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mT scaling of HBT radii
STAR preliminary
Various fits give different radii but mT scaling
of HBT radii is preserved in all fits
pp HBT looks like flow!
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Multiplicity dependence in pp
STAR preliminary
200 GeV
Rinv fm
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pp vs heavy ions - R(N,mT)
STAR preliminary
Similar mT and multiplicity dependence of HBT
radii in pp and heavy ions in STAR Is STAR pp
unique? Lets look at worlds results on HBT in
elementary particle collisions
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Femtoscopy in small systems
System vs GeV Facility Experiment
p-p 7.2 AGS E766
p-p 17 SPS NA49 -prelim
p-p 26 SPS NA23
p-p 27.4 SPS NA27
p-p 31-62 ISR AFS
p-p 44,62 ISR ABCDHW
p-p 200 SPS NA05
p-p 200 RHIC STAR
p-p 1.9 LEAR CPLEAR
p-?p 53 ISR AFS
p-?p 200 SPS NA05
p-?p 200-900 SPS UA1
p-?p 1800 Tevatron E735
?-? 126 ISR AFS
h-p 21.7 SPS EHS/NA22
System vsGeV Facility Experiment
ee- 3 SLAC Mark-II
ee- 10 CESR CLEO
ee- 29 SLAC TPC
ee- 34 TASSO
ee- 58 TRISTAN AMY
ee- 91 LEP OPAL
ee- 91 LEP L3
ee- 91 LEP DELPHI
ee- 91 LEP ALEPH
e-p HERA ZEUS
e-A HERA HERMES
R 0.5 - 1.5 fm
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My first impression
Can we do a direct comparison between
experiments?
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Parameterizations of 1D CF used in comparision
b/w experiments
RB2RG
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Summary

• Femtoscopy similar in pp as in AuAu _at_ 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
  arXiv0807.3569
• Same physics in pp as in AuAu and the only
  difference due to phase-space effects?
• possibilities
• spectra and HBT are insensitive to underlying
  physics (flow etc)
• they are sensitive the very different physics
  of AA and pp look coincidentally identical
• they are sensitive, and driving physics is the
  same

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