Zhangbu Xu (BNL) SQM2003 1 Resonances in Heavy Ion Collisions • Introduction – History/Techniques • Particle Yield – Thermal Description – Strangeness Enhancement • In-medium Effect • Time Scale Measurement • pT Spectra – Flow Effect – High pT Phenomenon Barannikova, M. Bleicher, G. Brown, P. Fachini, L. Gaudichet, Hallman,H. Huang, F. Laue, H. Long, R. Longacre, J. Ma, Markert , S. Salur, J. Sandweiss, E. Shuryak, A. Tai, G. Torr Ullrich, N. Xu, E. Yamamoto, H. Zhang
Resonances in Heavy Ion Collisions. Introduction History/Techniques Particle Yield Thermal Description Strangeness Enhancement In-medium Effect Time Scale Measurement pT Spectra Flow Effect High pT Phenomenon. O. Barannikova, M. Bleicher, G. Brown, P. Fachini, L. Gaudichet , - PowerPoint PPT Presentation
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• In-medium Effect• Time Scale Measurement• pT Spectra
– Flow Effect– High pT Phenomenon
O. Barannikova, M. Bleicher, G. Brown, P. Fachini, L. Gaudichet, T. Hallman,H. Huang, F. Laue, H. Long, R. Longacre, J. Ma, C. Markert , S. Salur, J. Sandweiss, E. Shuryak, A. Tai, G. Torrieri, T. Ullrich, N. Xu, E. Yamamoto, H. Zhang
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A little bit of historyWith the establishment of the hydrogen bubble-chamber, entirely new possibilities for research into high-energy physics present themselves. Results have already been apparent in the form of newly-discovered elementary particles. The first, very short-lived, so called, "resonance particle" was found in 1960. The Nobel Prize in Physics 1968
First time Invariant Mass was used (bump hunting)
(1952?)(1385) (1960)(892) (1961)(1405)
1411 (1967)
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Measurement Technique
• Mixed-event, Like-sign Background subtraction
• P-Wave Breit-Wigner function or Modified BWH. Zhang (STAR)
ISR STAR PreliminaryK*0 from p+p Collisions
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How Many Resonances?
Zhangbu Xu (BNL) SQM2003 5
How are we doing so far?e+e-: 50 particlesAA: 16Including stable particles
How Many Measured?
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Experiments
Exp 2 4* 0 f0 4* 2* 4
NA49 1 1 1
NA50 1
PHENIX 2
STAR 1 4 1 1 4 2 2
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What do we do with it?
)/)(exp(
)/exp(22
2
uss
q
qihbind
mm
m
mMEi
Y.J. Pei, hep-ph/9610329
More advanced: Thermal model
e+e-
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Significance of Feeddown
0.18K 0.30
0 0.50
K* 0.60
1.00f0(980) 1.00
p, 0.20
++ 0.80
* 1.00
* 0.80
Hadron Primordial Fraction
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• Brown-Rho Scaling• Rho Broadening• Low Mass Dilepton
measuring properties
Last Call for RHIC PredictionsNucl.Phys. A661 (1999) 205-260
• Chiral UA(1) symmetry restoration (J. Schaffner, D. Kharzeev, et al.)
Medium Effect in Dense Nuclear Matter
R. Rapp, et al
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How to Probe Early Stage?
• Modification in medium
• Decay quicklymatter exists 10-23s
• Small or no FSIleptons, photons, neutrino
Golden: J/
q
q
l
l
s
Small Branching Ratio(10-4), Low Production Rate
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-Production: Hadronic versus Leptonic Decay Channel
1) , K, p mean transverse momentum <pT> increase in more central collisions;2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow;
Star preliminary
1) , K, p mean transverse momentum <pT> increase in more central collisions;2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow;3) -meson seems flow differently.
J. Ma (STAR)
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Resonance Elliptic Flow v2
Coordinate phase space
K*
K
K*
K
X
Y
Ky
x
py
Px
22
22
xy
xy )(tan,2cos 12
x
y
p
pv
(A.M.Poskanzer and S.A.Voloshin, Phys. Rev. C 58, 1671 (1998))
Nuclei Non-central Collisions Hot System Elliptic Shape
• partonic flow?
• Daughters re-scattering K*0
v2 sensitive to coordinate phase space
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K*0 , Elliptic Flow v2
Statistical error only
Statistical error only
STAR Preliminary
• Observed Significant K*0, Elliptic Flow v2 vs. Centrality and pT
• Need more statitics
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Summary
• Resonances are Important Tools in Heavy Ion Physics– Particle Production – Matter Properties (particle properties)– Hadronic Decay Probes Freeze-out Dynamics– Flow/High pT Effect
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More Conventional Approach
J. Kapusta QM02
CERES
Hadronic channels consistent??
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)1385(
)1520(
)(
)(
)(
0
0
'
0
*
pK
p
KK
N
K
K
S
Hadronic Decay Mode
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Statistical models
T. Ullrich QM02
Dieter Röhrich, QM02
Statistical Model: Work Reasonably wellMore Resonance Data Coming