Strange Baryon Resonances

Christina Markert, Yale University

DOE Meeting at Yale, September 2003

• Motivation • Results (1520) ,(1385) and (1530)

from p+p, Au+Au and first d+Au Data• Summary and Future Plans

Christina Markert, Sevil Salur,

Richard Witt (Yale/Bern),

Ludovic Gaudichet (Subatech/Nantes)

Resonances in Medium

Short life time [fm/c] < < K* < * < * < * < 1.3<1.7< 4 < 6 < 13 < 20 < 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)

Resonance reconstruction in STAR TPC

(1520)

K-

p

(1520)

(1385), (1530)

*-+- -+-

*+++

*-+-

*+++ +++

* +

__ __

______ __ (1520) p +K- , p +K+

_

End view

Front view

Strange Resonances Signals in p+p at 200 GeV

*

(1385)

preliminary

mass 1.516 0.001 GeVwidth 18 MeV fixed

(1520)

Mixed technique

V0 technique

(1530)

Mixed technique

V0 technique

Resonance pt Spectra in p+p at 200 GeV

<pT> 0.92 0.03 GeV

(1520)

preliminary

(1385) and (1530) enough statistics corrections still underway

Mean pt in p+p at 200 GeV

<pt> for high mass resonances in p+p higher than particles with same mass ?

Helen SQM2003

(1520)

(1385)? (1530) ?

Strange Resonance Production in Au+Au Collisions

(1520)

No mass shift or width broadening visible

(1385)

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

Tch = 175 MeV

Resonance Production in p+p and Au+Au

preliminary

Tch = 120 MeV

Decrease from p+p to A+A at 200GeV : 70% ± 45%

UrQMD Microscopic model

First look at d+Au Data

(1385)

(1520)

(1530)

Summary + Future Plans

• Measure (1520) ,(1385) ((1530)) in p+p, d+Au and Au+Au collisions.• High mean pt in p+p for (1520) and (1385) . • Strange resonance/non resonance ratio shows decrease in Au+Au collisions compared to p+p collisions. Tchem =120 MeV (thermal model) .Or Time between chem. and kin. freeze-out = 5-10 fm/c (microscopic model).

Future Plans:• Complete d+Au and Au+Au analysis • write resonance paper (d+Au, p+p and Au+Au)

• 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 Au+Au run.

Pentaquark at STAR (first look)

p-p

Au-Aud-Au

STAR ideal decay mode is +->pK0

s

Signal estimation: 1.6 Million Au-Au events

= 3 peak.

No signal yet