1

Puzzles in strangeness Puzzles in strangeness (the heaviest light quark)(the heaviest light quark)

Rene Bellwied for the strangeness Rene Bellwied for the strangeness groupgroup

Wayne State University

u,d s c,b

5,10 MeV ~200 MeV ~1500,4500 MeV

~Tc

~<pT>thermalized parton

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What we have learned in WarsawWhat we have learned in Warsaw

1.) the flavor evolution of the yield scaling

from pp to AA

2.) the flavor evolution of recombination in R(CP) and v2

3.) the flavor evolution of R(AA)

4.) the flavor evolution of high pt correlations

3

Strangeness yields from pp to AA

Production not well modeled by Npart (correlation volume)

Add Cu+Cu

Canonical suppression increases with increasing

strangeness

and arenot flat

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Flavor dependence of scaling

• participant scaling for light quark hadrons• binary scaling for heavy flavor quark hadrons

PHENIX D-mesons (agrees withHaibin’s measurements)

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s-quarks are formed primordial Scaling according to quark content?

u, d – scale with Npart

s,c,b – scale with Nbin

p – Npart

K0s – 1/2*Npart + 1/2*Nbin

– 2/3*Npart + 1/3*Nbin

– 1/3*Npart + 2/3*Nbin

– Nbin

– Nbin

D – Nbin

Npart

Does strangeness “see” a differentcorrelation volume ?Is a different phase space densityrequired for strangeness production ?

Normalized to central data

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Nuclear Modification Factor Rcp

0-5%

40-60%

0-5%

60-80%

Y-4 K0s

√sNN=200 GeV

Baryon and meson suppression sets in at the same quark pT .

√sNN=200 GeV

Strange RCP signals range ofrecombination model relevance

Recombination scaling can be appliedto RCP as well as v2

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Identified Particle RCP

• strange RCP well behaved

• all particles have same RCP for pT>~5 GeV: dominance of fragmentation?

• no flavor dependence in fragmentation region ?

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Flavor independence of RAA ?

u,d dominated c,b dominated

no flavor dependence in energy loss ??

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RAA of Strange Particles

Particles with strange quarks scale differently to non-strange

Ordering with strangeness content!

s-quark

K0s, and h- all scale similarly

Au+Au

p+p

0-5%

√sNN=200 GeV

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Strange enhancement vs. charm suppression ?

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Quark Scaled RAA of Strange Particles

s-quarks scaled with NBin

u&d-quarks scaled with Npart

scaled with N part

s-quarks scaled with NBin

u&d-quarks scaled with Npart

scaled with N Bin

Need on this plot !! scales like the heavy flavor mesonsAnalysis focus on 40 Million pp events and year-4

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Flavor dependence of 2-particle correlations● 50% Proton/Anti-Proton● 95% π

● Λ● Anti-Λ● KS

0

● 50% p/pbar■ Λ□ Λbar● 95% п■K0

s

Nch

/NT

rigge

r

pTTrigger

Au+Au 0-5% 1.0<pTAssociated<2.0

Same side associated yield:-Ridge effect ( correlation) ?-Coalescence effect ?-Fragmentation effect ?Need more year-4 stats and bins

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SummarySummary

Strange particles are unique in the RHIC environment. They apparently carry the

primordial information of the produced s-quarks, in particular in the high pt regime

of their spectrum. They are much more abundant than heavy flavor particles and

thus can be used to extract detailed information on particle production

mechanisms at RHIC energies.

There is much more to come from strangeness

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Ongoing analyses and QM presentationsTalk:

S.Salur System size and energy dependence of strangeness production

Posters:

G. van Buren  The Ratio  at RHIC 

B. Bezverknhy Initial studies of two particle azimuthal correlations using baryons in collsions at RHIC

H. Caines  The effects of varying the correlation volume on strangeness M. A. Lamont  High momentum strange baryon anomalies in heavy ion collisions at RHIC  C. Markert  The influence of medium properties on the resonance production in RHIC collisionC. M. Mironov  STAR measurements of strange hadron R AuAu and M. G. Munhoz  Measurements of K0 and  production in collisions at 62 GeV Au+Au  F. Simon Forward lambda production and nuclear stopping power in d+Au collisions at RHICJ. Speltz  Energy dependence systematics of strange and multi-strange particle production R. Bellwied Strange particle production mechanism in pp collisions at RHIC

Analyses:

M.Lamont, A.Timmins: strange baryonsJ.Speltz, J.Takahashi, M. Munhoz, J.Faivre, M.Estienne: Multistrange baryonsC.Markert,R.Witt,S.Salur: resonancesG.Van Buren:Sigma0B.Bezhverkhny,J.Bielcikova, C.Nattrass, L.Gaillard: identified particle correlationsH.Caines: scalingF.Simon: forward physicsC.Mironov, H. Jiang, L. Barnby,: dA strangeness in dAM.Hainz, R.Witt, C.Mironov, J.Adams, RB: strangeness in ppC.Mironov: kinksS.Kabana, M. Heinz, C.Markert: pentaquarksS.Lapointe, K.Foranzier, J.Takahashi, M.Munhoz, RB:: SVT analysis

Papers in GPC: high pt strange baryons, strange resonancesPapers close to GPC: strangeness in pp, strange particle correlations, forward Lambdas, 62 GeV strangeness