Lambda(1520) Produktion in zentralen p p- und Pb Pb- St

1
Strange Baryon Resonances
Christina Markert, Yale University

• Motivation
• Results ?(1520) ,?(1385) and ?(1530)
• from pp, AuAu and first dAu Data
• Summary and Future Plans

Christina Markert, Sevil Salur, Richard
Witt (Yale/Bern), Ludovic Gaudichet
(Subatech/Nantes)
DOE Meeting at Yale, September 2003
2
Resonances in Medium

• Short life time fm/c
• ? lt ? lt K lt ? lt ? lt ? lt ?
• 1.3lt1.7lt 4 lt 6 lt 13 lt 20 lt 40

• Strangeness enhancement ?
• Temperature at chemical freeze-out ? ? Yield
  (Thermal models)
• Time between chemical and kinetic freeze-out ?
• Rescattering and regeneration of resonance
  decay particles
• ? Yield and pt spectra (Microscopic models
  UrQMD)

3
Resonance reconstruction in STAR TPC
?(1520)
?(1385), ?(1530)
End view
Front view
4
Strange Resonances Signals in pp at 200 GeV
?(1520)
Mixed technique
Mixed technique
mass 1.516 ? 0.001 GeV width 18 MeV fixed
?(1530)
V0 technique
V0 technique
5
Resonance pt Spectra in pp at 200 GeV
?(1520)
preliminary
ltpTgt 0.92 ? 0.03 GeV
?(1385) and X(1530) enough statistics corrections
still underway
6
Mean pt in pp at 200 GeV
?(1385)?
?(1530) ?
?
?(1520)
Helen SQM2003
ltptgt for high mass resonances in pp higher than
particles with same mass ?
7
Strange Resonance Production in AuAu Collisions
?(1520)
?
?(1385)
No mass shift or width broadening visible
8
Resonance Production in pp and AuAu
UrQMD Microscopic model
preliminary
Tch 175 MeV
Tch 120 MeV
Thermal description Chemical freeze-out
temperature Tch 120 MeV Microscopic model
Time span between chemical and kinetical
freeze-out ? 5-10 fm/c. ?(1385) ? ?
analysis on the way
Decrease from pp to AA at 200GeV 70 45
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First look at dAu Data
?(1385)
?(1530)
?(1520)
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Summary Future Plans

• Measure ?(1520) ,?(1385) (?(1530)) in pp, dAu
  and AuAu collisions.
• High mean pt in pp for ?(1520) and ?(1385) .
• Strange resonance/non resonance ratio shows
  decrease in AuAu collisions
• compared to pp collisions.
• ? Tchem 120 MeV (thermal model) .
• Or ? Time between chem. and kin. freeze-out ?
  5-10 fm/c (microscopic model).
• Future Plans
• Complete dAu and AuAu analysis
• write resonance paper (dAu, pp and AuAu)
• Put together results from (?,?,?) with ?, ?,
  K and ?,
• compare it with theoretical predictions.
• Resonance meeting at Yale in Dec2002,
• plan to have another resonance meeting later
  this year.
• Full pt spectra for ?(1520) and ?(1530) with
  higher statistics from upcoming AuAu run.

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Pentaquark at STAR (first look)
STAR ideal decay mode is Q-gtpK0s
p-p
Signal estimation 1.6 Million Au-Au events
3 s peak.
No signal yet
Au-Au
d-Au